the size is more of an indication of breeding in terms of how big of a crest they will get. males crests generally are a lil smaller as chicks, but a big crest in one variety might be a small one in another.
Well from looking at pics of other Polish chicks I have to assume that one is a black with white crest, 2 are buff, 2 are silver and one of my other silvers died yesterday for no reason. The 2 buff and the 2 silver have very small puffs and the black one has a huge puff it already looks so funny. They are 1 week old.