They really are a different breed, you know. In the Bears vs Bulls stage out on the gym floor, the differing weight lifting and training styles of Gay MuscleBull men vs The MuscleBear Meat Heads plays out. When you study the genetic composition of these two disparate body somatotypes, it often boils down to the Endo-Meso hybrid (Lugnuts) vs the pure Meso or Meso-Endo types (Meatheads).
BULLS vs BEARS : LUG-NUTS
The thick-boned and well-padded Endomorphic-leaning MuscleBulls chow-down (up?!) in bulk to bulk up a heavy-set olympic Powerlifting frame ideal shoving uber-heavy sets of weights around. They never were predisposed to stripping down to lean, detailed, sculpted and striated muscle mass any ways. So they go for what's attainable: Lugging, dragging, shoving, hefting ridiculously heavy objects like #300 concrete balls and whatnot for sport -- ala the Strong Man Games.
BEARS vs BULLS : MEAT-HEADS
Ah, but your lean and beefy Mesomorphic-leaning 'Classic' MuscleBears - now that's a different stripe. They may go hard and heavy with the weights too, but like their diet it's far more controlled and geared for exacting precision. "Make _that_ muscle _here_ separate _here_, and bring it's size to _this_ and it's curve to _there_." The diet that feeds the Meat-Head Bear muscle machine is intrinsically different 'cuz sheer-BULK isn't the point.
All in all, two very differently composed physical types and patterns of body-fat distribution: Both inherently very muscular. But form follows function. Heavy set guys like MuscleBulls seem happiest doing what their bodies were designed for: Heavy Lifting, like oxen hooked to a plow.
Image Credit: Unknown - From a bygone era where wearing a Fig Leaf for support pre-dated the invention of the Jock-Strap.