Flash your eyes from Ronnie's bicep to Arnold's quickly, Arnold's piss all over Ronnie's, it's like a before and after.
And yea, Arnold's taper is miles better, his chest is way thicker above a smaller midsection and he's much more refined.
That's easy, in this pose Arnold has a smaller waist, a thicker chest, better taper a lot more separation in his quads better arms although some might disagree with that but look at the triceps development Arnold takes that one, they both have great biceps although I prefer Arnold's and better calves. That's off the top of my head.