mulching blades swirl the grass clippings around a few times and chop them up again and again which makes them small enough to fall between the grass onto the dirt. This is awesome during the summer because the grass clippings disappear, its even more awesome in the fall because you can mulch fallen leaves the same way.
High lift blades create more of an updraft than normal blades, this pulls the grass up for a more even cut.
Gator Blades look completely ridiculous and would badly deform if you run over anything not grass.. I'd stay away.