Well the difference is in one case, you're getting a guy who has had success at the NHL level before and in the other, you're getting a draft pick who has proven exactly nothing. Kari Lehtonen, David Legwand, Andrei Zyuzin and Oleg Tverdovsky are all #2 overall busts from the last 15 years. There have been many good players in that span as well that have gone #2, but how many of them would you take over Phil Kessel right now?
As for the Wesley trade, I was simply stating it as an example. Sergei Samsonov had 2 29 goal, 70 point seasons and that was pretty much it, Kyle McLaren played over 70 games only twice in 7 injury plagued seasons with the Bruins and was a minus player more often than not. Wesley post trade? 2 Stanley Cup runs in Carolina going +12 in one and +16 in the other, averaging over 20 minutes per game during his playoff career in Carolina, winning a Cup and being the leader of a group of unsung defensemen in both runs.
How did Carolina win the Wesley trade? Stanley Cups - Carolina 1, Boston 0.