pullet or cockerel

[TXchickenNewb]

Hello!
I was hoping for some input on a chick I picked up a couple weeks ago from the local feed store. Both are supposed to be ameraucana pullets- they are now about 3 weeks old. When can I tell if they are for sure pullets. My concern is one is now about double the size of the other. Not sure if that’s an intimation of male or female or not. Any input would be appreciated. New to owning chickens. Pictures below of both.
Thank you!!

 

[Finnie]

They are both girls. Do you see the salmon coloring coming in in their breasts? That is a female coloring. In breeds where the female has a salmon breast, the male will usually have a black breast. So you would see a lot of black feathers starting to come in there.

 

[TXchickenNewb]

They are both girls. Do you see the salmon coloring coming in in their breasts? That is a female coloring. In breeds where the female has a salmon breast, the male will usually have a black breast. So you would see a lot of black feathers starting to come in there.

Thank you! Good to know!