uos vs os modules

How does the uos module differ from the more standard os module? Should I be using one over the other if I want to read/write arbitrary files (not necessarily images, gifs, or videos) to and from the SD card?

Same question applies to the uio and io modules of course.

Um, I think they are the same but use the uio/uos versions. MicroPython specs them instead of the standard ones.

They both link to the same module, some googling verifies this: