I wanted to know the difference between the two breeds. The yellow one is the Giant and the black one is the regular one. The regular one is bigger than the Giant breed and they're the same age. (I apologize if this is the wrong forum to ask this question)
They are not different breeds, but rather different sizes.
From my knowledge the smaller one is most likely a bantam, and the larger one is a standard sized, also know as large fowl.