What is the exact difference between Computer Science and theoretical Computer Science StackExchange sites?
Does Computer Science really mean Applied Computert Science?
Computer Science Stack Exchange is for students, researchers and practitioners of computer science.
Theoretical Computer Science - Stack Exchange is a question and answer site for professional researchers in theoretical computer science and related fields.
cs.SE does have a broader range of acceptable topics than cstheory.SE, but the key difference if the level they're aimed at. cs.SE is for basically anyone interested in Computer Science (within scope). cstheory.SE is meant for active researchers in theoretical CS, and the questions should be not-too-far from research level work (included graduate level questions).