Hmmmm....I found this post which says it's the underside of the foot that tells the difference.
https://www.backyardchickens.com/t/176156/black-australorp-or-black-jersey-giant#post_2115504
Quote:
Murray McMurray substituted my BA hens for JG hens but shipped the BA males I ordered.
Can anyone tell my if this chick is a BA or JG? I have heard that the black legs and feet are a telltale trait, but I can't recall for which breed.