Hen or Roo?

[Pit Bull Farm]

I got these two chickens together and I was told they are both Hens. As they got bigger the comb(Is that what you all it?) is getting bigger on the one. Can it just depend on genetics? can a hen have a bigger comb than another one? Sorry for the silly question.
They are amost full size chickens, her is the one that looks "normal"

This is the bigger one

They are a mixed breed could that be the reason they do not look the same? Thanks

 

[chicksrocka]

I'd say they both look like hens. How old are they?

 

[aank4]

Do you know if they are siblings? Or how old they are? It's possible that the second one is a roo if they're the same age and from the same hatch, except I'd expect he'd be crowing for you by now if he were male. First one looks female to me for sure. If your second isn't letting you know (loudly) that he's male - maybe she's a she!

 

[houndit]

I think they are both hens. I am not sure. It is possible for one hen to have a larger comb than another.

 

[Pit Bull Farm]

They did hatch together and I am guessing hey are about 4-5 months old. That is what I was thinking is if she was a Roo she would have started crowing. she acts like a hen too. But when her comb started to grow I got worried.....
Now I do have a rooster the same age and from the same place, and he is not crowing yet. The only difference is you can tell he is a rooster. Here he is

 

[TheNewMrsEvans]

she looks to have hen feathering on the neck...could you take a pic of her whole body incl tail? if it was a he you'd have bigger curving tail feathers too.
She should lay you an egg soon if they are that old!