prosfilaes
Adventurer
But the difference was that when 4e came along, the OGL meant Pathfinder was able to come along, favouring a different play style but still recognisably being D&D.
I don't think that was the difference. 3rd Edition was coming off 2nd Edition, which was long in the tooth, and not really loved. (Look at how little retro support there is for 2e.) They made a very good system, and at the same time kept it very faithful to the older editions of D&D. When they made 4e, 3e was still a very well loved system, and a very good system; but they choose to kill several sacred cows and make a system that, whatever virtues it may have, is very different from 3e.
My DM still runs 3.5, and I've seen a number of advertisements for 3.5 groups. A recent poll here ( http://www.enworld.org/forum/general-rpg-discussion/308611-what-version-s-d-d-do-you-play.html ) came up with almost as many 3.5 players as Pathfinder and D&D 4 (72/77/78), so I don't think the split can be attributed to Pathfinder alone.