GreyLord
Legend
It is most definitely not just presentation. The power structure is a huge difference in the games. The Healing surge (and its support) is another. Both of those differences are major transformations.
Healing surges aren't part of the core anymore than the extra spell the Cleric can cast the +1 portion of his spell list (for ex. 2+1, or 3+1 etc) is in 3e. They aren't what I would consider part of the core dynamic per se...D20 has it's core dynamics and rules which 4e adheres to pretty strongly, a core which didn't exist in previous editions of D&D/AD&D, but does in 3e, 3.5, and 4e (and Pathfinder for those of us that play PF).
For example, PF has a different dynamic of how 0 level spells work...as well as how skills are gained (though they still can be compatible with 3e DC's with slight tweaks), but it still has the core mechanics of D20/3e.