I think Sophia was actually bustier. She just didn't show off as much cleavage, or use push-up bras, padding, etc, as Jayne did. Jayne was really about average chest-wise. But overall, an absolutely gorgeous woman! She wasn't nearly as busty as other women from the same time period, such as....say ... Elaine Reynolds!

(I believe this photo has probably already been posted, but it's been a while.)