With a big caveat. The chart shows that C10, U1, and v10 are all equivalent in terms of the nominal speed, but in fact they are not equivalent in terms of real-world flash memory performance - at least not on all devices.
The issue is that because of how flash works, its performance depends critically on how you use it. If you have a basic flash drive, and access it sequentially, you'll see the rated performance; if you access it non-sequentially, performance can drop A LOT. I'm not talking about losing 10% of your performance, I'm talking about losing more like 90%. I hit this on a tablet product I was working on, and I had to develop my own flash memory benchmark to account for it.
The SD card rating standards have developed over the years - early devices only did sequential access, so a fancy testing scheme wasn't needed; but for more complex devices, like modern video cameras, you need to ensure that the flash card delivers the rated performance under more complex usage scenarios. You could be recording video and audio in separate files - like my camera can do - or you might be recording a separate file of meta-data, or gyro data, or depth data, or whatever, in parallel with the video. Or all of the above.
So the three sets of rating standards use different testing criteria. I don't know exactly what they are - this information isn't exactly public - but the "C" standard is very simple, whereas the "v" standard is much more complex - it tests the speed while writing multiple streams of data at once, which more closely matches how some cameras record video. Which in practice means that to pass "v", an SD card needs more RAM buffers internally, a more sophisticated controller, stuff like that.
So for video, or certainly for high-standard video (4k, 10-bit, etc), you really need a card with a "v" rating.
I explain all this in a video I made: https://moonblink.info/MudLake/tech#Cards
