Snap-On is different from other major tool brands in several ways. You won't find them sold directly through Home Depot or Amazon. The quality of Snap-On tools is generally considered to be better ...
Makita may not have as stellar a reputation as Snap-On, but the former still has some tools that, on paper, are more powerful ...
Snap-On is one of the most expensive toolmakers around, that's why many mechanics use these tool brands instead.