You're looking at a half cm or so difference in top tube and seat tube measurements. Assuming the TT measurement is for a horizontal tube or effective length of a sloped or curved tube, there isn't going to be much difference in overall size, but there might be a noticable difference in geometry. I have two hybrids right now. One has a 21.5" seat tube and the other 22" but the standover is almost identical and the bike with the 21.5" seat tube actually feels "bigger" because of a slightly longer top tube.