You own the license and can sell the license (generally), not the actual game. To use an analogy, if you buy and own a car, you could take it apart or replace any part you like, put the engine into another car, etc. You can't do the equivalent with a typical game and other propertary software, at least not legally, because you don't own it, you just own the right to use it.

Might not make a noticable difference to most people because most people don't do much with games/software apart from using it, but there still is a difference.