It will be interesting because even their muscle tones will differ depending on they style of riding. I'll start:
I just picked 2 of mine. Beauty is a 15 year old mare, was bred mostly for halter, (using both a mare and a stalion that were bred for halter) with Western Pleasure second in mind:
Her son Riley was bred for western pleasure first and english second (using a leggy stallion that was bred for western pleasure)
You can see with just these two the difference in the body styles...