Its not just a show thing, its a purebred thing. Silkies arent supposed to have straight combs, they are supposed to have small rose combs. Defect just means that something about the bird isnt up to par with breed standards. This means nothing if you have them for pets, or not concerned with showing or breeding to standard.
Yes I agree, the second one looks like a cockerel to me.
As for the first one... I'm not sure. I agree, it does look different then your second one, but that doesn't mean it's a pullet.
I would give that one some more time.
Good luck with them, they are very cute!