The two commercial models that are the most popular are the zone start 3-speed RWD self propelled with either a Honda or Kawasaki engine (22295 & 22297). They are expensive. Are you sitting down? $2000. Frankly, the mower is massive overkill for a homeowner.
The deck is different than the black homeowner 21" Super Recycler deck. It is MUCH thicker and a different aluminum alloy, it is reinforced with with steel wear plates on both sides, has an engine protection bumper, and has a steel crankshaft protector. The handles and mounting hardware, wheel mounting hardware, and height adjusters are all much heavier. The 9"x2" wheels have rubber tires with ball bearings. The entire mower is MUCH heavier. The transmission and drive system is Toro's outstanding Heavy Duty belt drive 3-speed that is legendary for it's durability. I never had to rebuild one.
The Kawasaki FJ180V engine is a 179cc OHV full pressure lube engine with oil filter, steel sleeve, and 1" forged steel crankshaft supported by ball bearings. The Honda GXV160 engine has similar specs but is a 163cc OHV with splash lubrication. Both have 1 gal fuel tanks.
The commercial mowers are manufactured in the USA, so are the black homeowner 21" Super Recyclers. The steel deck 22" Recyclers are manufactured in Mexico (IMO by MTD but nobody is willing to fess up to this).