The Small Blind is the dealer
But, the SB acts first before the flop (as you would expect for the SB)
but then acts last after the flop (as you would expect for the Dealer)
Therefore i suppose the SB/Dealer is in early position before the blinds and late position after. Overall the Dealer/SB has the positional advantage I would say.
The Big Blind is dealt their first card before the Dealer, despite what some internet sites will tell you.
Also in the change from 3 players to 2 players the BB moves to the next player in order, which may result in the Button having to move out of turn. (i.e If the Dealer goes out 3rd then the button appears to move backwards to accommodate the Blinds moving forwards)