I've always thought that if it was a T, that meant that it was a little bigger in the bottom to accommodate a diaper. I've found that if it had a T, it was also a little shorter. As far as 2T, 2 and 24 month, it all depends on the brand. The companies that do 24 month usually won't have 2T or 2 sizing. I find that 24 month stuff are slightly smaller than 2 and 2T.