I have three 17 week old EEs that I bought as day old chicks. Two of them look very similar, but I've just recently noticed that "Chickie's" comb is much larger than "Fluffy's". There has been no crowing or egg laying from any of them yet, but they seem to be more aggressive with each other lately. I don't know if it's just puberty, or irritability from their inability to free-range for a couple of weeks due to deep snow, but they've really been in each other's faces alot these days...fluffing their neck feathers and "posturing". Chickie, the one with the more pronounced comb, was the smallest of the chicks and has always been the most affectionate. All three are about the same size now. Could Chickie be a roo? I can attach full body pics if that might give more clues to sex. I included a pic of Fluffy for comb comparison.
Above pic is Fluffy
This is Chickie
Another pic of Chickie
Above pic is Fluffy
This is Chickie
Another pic of Chickie