I think what Scorch said is key. Note that whether he stopped at 220 grit or 440 grit, it was followed by buffing. Buffing and polishing compounds work a bit differently than abrasive cutting compounds. Where abrasives in the coarser grades remove a lot of metal, polishes remove amounts disproportionately smaller than their particle size and also smear surfaces smooth microscopically. I recall reading how, even with something as hard as glass, electron microscopes found small particles of polishing compound
under the polished surface of glass lenses, due to the glass having smeared over top of it.
If you apply buffing to a surface that was first abraded by something much coarser, it will remove the microscopic surface variation except down in pits, and that will look much more polished than the raw product of the abrasive grit did.
It's also the case that the choice of abrasive affects this. The sharp shards of silicone carbide wet/dry paper will cut faster but leave a duller, more gray surface than the rounder particles of aluminum oxide do. If you want to see this for yourself, go to a Woodcraft store where they sell the white (aluminum oxide) Norton sand paper from 80 down to
400 grit. You can run the 220 grit wet/dry, wipe the surface with alcohol to get the traces out, then repeat with the aluminum oxide 220 over a portion of the surface to see the difference. You can even buff them both to see the difference.