Quote Originally Posted by johnw View Post
Just look at the specs posted earlier in this thread. The sequential write speed is 340MB/s for 128GB and 450MB/s for 256GB. That is the main difference. The 128GB also has a smidge less 4K random IOPS at high QD than the 256GB, but that is a totally irrelevant spec for most usage patterns.
From what I've seen, real world testing and specs and what something should do don't match up that well all the time.