Random IO

Random read/write performance matters if you copy a lot of small files or use the drive as storage for games/applications that are directly started off the drive.

Sequential IO

Sequential performance is relevant when you copy large files—videos, for example.

Sustained Write Speeds

Sequential write speeds are a constant 250 MB/s, which is low compared to competing USB 3.2 portable SSDs. The good thing is that these speeds are guaranteed for the whole drive—some other drives will start out high and drop to low rates after a certain amount of data has been written, when the pseudo-SLC cache is full.