All BS aside... what truly differentiates a Kung Fu style?

Now before you go in depth into theories, origins, and mysticism etc., try to define differences in styles.

To me it's "this style is this body of forms." Period. If you say you're X style, you know a collection of forms that are catalogued as X style. Is there really that much of a difference between X and Y styles? NO. Just a different body of forms.

Yeah, you'll all start to theorize about internal and external and chi and southern and northern and yada yada yada but in truth what stops somebody who learns Xing Yi from learning Bung Bo? nothing, and then you'll get into Chi Sau or whatever but guess what, all advanced players in any style have some type of sensitivity training in there regimen. Be it Chi Sau, mantis playing hands, eagle claws qin na drills, tai chi's pushing hands, whatever... it's all the same. Two people practicing sensitivity. Oh yeah... chi gung... anybody can learn chi gung...

So are there any different styles, or are there just some different ways to collect forms?