Quote:

XNA is a framework and not a engine.



This is the key point to remember.

XNA is like MFC for games. Frameworks make it easier to write your game by handling the lower level stuff (rendering, playing sounds, etc.) but they still require you to do the rest of the programming.

3DGameStudio is a game engine. Game engines handle more of the core features in games (culling, memory management, collision, physics, message passing, networking, etc.). These are all things you would have to program yourself if you use a Framework.

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