Double breasted is a suit. Single breasted is someone who has had a mastectomy. The correct terms are Broad Breasted and Standard, as in the original post.
Besides weight, there are major type differences between the two. Standard Bronze have an upright carriage with a triangular body shape, just like the birds pictured in the Standard of Perfection. Broad Breasted Bronze have a horizontal carriage, with an almost rectangular body shape. Their legs are usually placed in the center of the body to help carry their immense weight, vs a further back placement on the Standards. Once you see a mature BB, there is little mistaking it with a Standard. The BB are more massive in most every respect.
Everyone thinks that their birds are beautiful and precious, but unless they have been bred to exacting standards and continuously slected for show qualities, it is extremely rare for one to measure up well to those which have, especially if obtained from a source where the exact breed is unknown, let alone show traits.
