Technical Guides and Comparisons
These guides answer the comparison questions buyers ask before specifying a part: whether TF and MicroSD are the same thing, which physical format fits a product, what cell type and speed class actually mean, where the consumer/industrial line falls, and what a NAND grade does and does not tell you. Each one is written to be usable on any supplier’s product, not only ours — a comparison that only describes our own range is marketing, not a guide.
What these guides cover
16 comparisons, organised by the decision they support. If you are choosing a physical format, start with the first group. If you are checking whether a quoted speed number means what you think it means, the third group is where most specification errors get caught.
| Guide | The question it answers | Group |
|---|---|---|
| TF Card vs MicroSD | The same physical format, two names, and one reason both are still used. | Format and physical package |
| UDP vs COB vs PCB | Three physical formats, three different places in your product. | Format and physical package |
| SLC vs MLC vs TLC | Bits per cell, endurance, cost — and why the label alone is not enough. | Silicon: cell type and grade |
| U1 vs U3 vs V30 | Four markings, four different things measured, one that matters for you. | Speed: classes, interfaces and what is actually measured |
| A1 vs A2 | Random IOPS, not video speed — and only relevant if you run apps from the card. | Speed: classes, interfaces and what is actually measured |
| Consumer vs Industrial Flash Storage | Temperature range, endurance, supply life — and what each costs. | Silicon: cell type and grade |
| NAND Flash Grades and Sourcing | Grade, source, and the difference between the two questions. | Silicon: cell type and grade |
| USB 2.0 vs USB 3.0 | The sustained rate, not the peak figure, is what you are paying for. | Speed: classes, interfaces and what is actually measured |
| Metal, PVC or Wood USB Drive Body | Branding, durability and cost are decided by the body material. | Branding and USB body selection |
| Custom USB Drive vs Standard Stock Drive | A stock drive is somebody else’s specification with your name on it. | Branding and USB body selection |
| Why a 128GB Card Shows 119GB | The arithmetic behind the shortfall, and how to spot a genuine fake. | Capacity and file systems |
| FAT32 vs exFAT for Memory Cards | The practical difference is the 4 GB single-file limit: FAT32 caps a file at 4 GB, exFAT does not. SDHC ships FAT32, SDXC ships exFAT, and the device — not the card — decides what it can read. | Capacity and file systems |
| SDHC vs SDXC | SDHC tops out at 32 GB and uses FAT32; SDXC goes to 2 TB and uses exFAT. Both share the same microSD physical body for TF cards — the difference is the capacity tier and what your device can read. | Capacity and file systems |
| Sequential vs Random Read/Write for Flash | Continuous recording is almost entirely sequential write, and that is exactly what SD Speed Classes certify as a minimum sustained rate. Random I/O depends more on the controller than on the raw NAND. | Speed: classes, interfaces and what is actually measured |
| USB-A vs USB-C | USB-A and USB-C are connector shapes, not speed grades. A USB-C port can be USB 2.0 and a USB-A port can be USB 3.x. Confirm the connector your recipients actually use before you order. | Speed: classes, interfaces and what is actually measured |
| USB Flash Drive Real Speed vs Advertised USB | A USB 3.2 port signals at 5–10 Gbps, but a real USB flash drive may read at 20–150 MB/s. The interface rating and the actual throughput are different numbers. | Speed: classes, interfaces and what is actually measured |
Format and physical package
Before any electrical question comes a mechanical one: which body goes into the product, and what does a buyer mean by the name on the datasheet. These two guides settle the naming and the package.
TF Card vs MicroSD
The same physical format, two names, and one reason both are still used.
UDP vs COB vs PCB
Three physical formats, three different places in your product.
Silicon: cell type and grade
Two different questions that are routinely confused. Cell type (SLC / MLC / TLC) describes how many bits each cell stores. Grade describes how a die was screened and where it came from. Neither one alone tells you how a card will behave in the field.
SLC vs MLC vs TLC
Bits per cell, endurance, cost — and why the label alone is not enough.
NAND Flash Grades and Sourcing
Grade, source, and the difference between the two questions.
Consumer vs Industrial Flash Storage
Temperature range, endurance, supply life — and what each costs.
Speed: classes, interfaces and what is actually measured
Speed markings answer different questions and are not interchangeable. A speed class certifies a minimum sustained write rate; a USB interface generation describes a signalling rate; random IOPS describes small-block behaviour. Reading one as a stand-in for another is the most common specification error we see in RFQs.
U1 vs U3 vs V30
Four markings, four different things measured, one that matters for you.
A1 vs A2
Random IOPS, not video speed — and only relevant if you run apps from the card.
Sequential vs Random Read/Write for Flash
Continuous recording is almost entirely sequential write, and that is exactly what SD Speed Classes certify as a minimum sustained rate. Random I/O depends more on the controller than on the raw NAND.
USB 2.0 vs USB 3.0
The sustained rate, not the peak figure, is what you are paying for.
USB Flash Drive Real Speed vs Advertised USB
A USB 3.2 port signals at 5–10 Gbps, but a real USB flash drive may read at 20–150 MB/s. The interface rating and the actual throughput are different numbers.
USB-A vs USB-C
USB-A and USB-C are connector shapes, not speed grades. A USB-C port can be USB 2.0 and a USB-A port can be USB 3.x. Confirm the connector your recipients actually use before you order.
Capacity and file systems
Where a capacity number comes from, why it does not match what the operating system reports, and which file system a host will actually mount. These are arithmetic and firmware questions, not silicon questions.
Why a 128GB Card Shows 119GB
The arithmetic behind the shortfall, and how to spot a genuine fake.
FAT32 vs exFAT for Memory Cards
The practical difference is the 4 GB single-file limit: FAT32 caps a file at 4 GB, exFAT does not. SDHC ships FAT32, SDXC ships exFAT, and the device — not the card — decides what it can read.
SDHC vs SDXC
SDHC tops out at 32 GB and uses FAT32; SDXC goes to 2 TB and uses exFAT. Both share the same microSD physical body for TF cards — the difference is the capacity tier and what your device can read.
Branding and USB body selection
For branded drives the enclosure is the product the end user holds. Material decides durability, print method and unit cost together, and a stock drive versus a custom one changes who owns the specification.
Metal, PVC or Wood USB Drive Body
Branding, durability and cost are decided by the body material.
Custom USB Drive vs Standard Stock Drive
A stock drive is somebody else’s specification with your name on it.
How to use a comparison guide
Each guide is written to be usable with any supplier, not only with us. That is deliberate: a comparison that only describes one vendor’s range cannot help you judge a competing quotation, so it is marketing rather than a guide. Where a guide states a standard or a limit, it cites the body that defines it — the SD Association for card capacity, speed classes and application performance classes, USB-IF for interface signalling rates, and Microsoft for the FAT32 and exFAT file-system limits.
Read them in the order that matches your decision. If you are still choosing a format, the format group decides the mechanical fit first. If you have a quotation in hand and want to check the numbers on it, go to the speed group and compare the marking against the workload you actually have. If the question is commercial — grade, sourcing, packaging — the silicon and branding groups cover the vocabulary you need to ask a supplier a question it cannot answer vaguely.
What a guide cannot tell you
A comparison can explain what a marking means and where the limits sit, but it cannot tell you how a specific part will behave in your product. That depends on the controller, the firmware, the host, the workload and the batch. For that you need a sample tested against your own use case. The guides are written to help you ask the right question at that stage — not to replace the test.
Buyer questions about these guides
Are TF card and MicroSD the same thing?
Yes. TF (TransFlash) is the original name SanDisk and Motorola used; the SD Association later standardised the same physical format as microSD. The card, the slot and the electrical interface are identical, so a TF card works in a microSD slot and vice versa. The name on the packaging is a naming convention, not a specification difference.
Does a higher speed class mean a faster card in my device?
Not necessarily. Speed classes such as U1, U3 and V30 certify a minimum sustained sequential write rate, which is what matters for continuous video recording. If your device writes small files randomly — a data logger, an embedded system with a database, an app running from the card — random IOPS (the A1 / A2 ratings) describes your workload better. A card can carry a high video class and still be slow for small random writes.
Why does a 128GB card show less than 128GB in my operating system?
Two effects stack. First, flash vendors count a gigabyte as 1,000,000,000 bytes while operating systems report in binary units of 1,073,741,824 bytes, so the same capacity appears smaller. Second, the file system and controller reserve space for metadata, wear levelling and bad-block management. A shortfall in the range of a few percent is normal arithmetic; a shortfall of tens of percent suggests the card is not what it claims to be.
Which file system should a card be formatted with?
The one your host device can read. FAT32 is the widest-compatibility choice but caps a single file at 4GB, which rules it out for long continuous recordings in one file. exFAT removes that limit and is the standard for SDXC, but older devices may not mount it. The card does not decide this — the host firmware does, so confirm host support before you specify a format.
Is a NAND grade the same as a quality guarantee?
No. A grade describes how die were screened and where they came from, which affects consistency and expected life, but it does not by itself guarantee behaviour in your product. Two suppliers can quote the same grade and deliver different results depending on controller pairing, firmware and test coverage. Ask what was tested and how, not only which grade label applies.