Cochin Hens - Page 2
I think merely because one is a little younger or simply maturing a little more slowly...they both have very patchy coloring and most importantly, the red bars on the wing bows...a hallmark of rooster.
At 3 to 5 months of age, yes, as roosters get large big red combs early, while hens get moderate combs just before point of lay...unless a breed like Leghorn where the girls get some impressive combs too...but the Leghorn guys still far outshine them.
What a rooster alone will get is saddle feathers, the spiky cascade of feathers just before the tail, and red wing bars...typically will also have very colorful patches....and of course, they crow.
Girls will be more uniform in color pattern, have soft rounded feathers (some can get a bit of spike at the hackle), and moderate combs that come to "life" at point of lay, so a full grown hen and a maturing teenage boy can look similar, until the secondary sex feathers kick in and the comb comes to full size.
If it crows...it is almost always a rooster, barring a very odd occurrence where occasionally a hen will have a hormonal change and she can crow...but that is rare.
You have two roosters, without a doubt.