Subtle differences, and your LBS might have some you can eyeball to get a feel for what might work. I see they have one designed to take clip-ons for instance. It looks like FSA has 125/80 on all its compacts, but if you go to that page, you'll see a handlebar FAQ pdf as well which might be of use. And the individual product pages might have drawings that will show differences like curve shape. At least you'll see the full range there, rather than the run-outs and NOS that are picked up by the online retailers (which may well suit, especially at the price vs what we pay retail).