Hi Bill!
The biggest difference, for me, has been that I finally got the CORRECT bra size! Since support was even a bigger (grin) issue than before and I knew that bras would be more expensive, I took the time to get professionally fitted and I'm REALLY glad I did that!
Other than the fact that my bras fit much better now because of getting the right size, I haven't noticed a particular difference in how they wear and feel. Except, of course, that now my waist looks even smaller and I like that a lot! 