Well, they certainly have nonempty intersection, but I'd say none is contained in the other. With leaps, the problem is also about accuracy, not just tension. If your arm movement doesn't come form the arm itself but from the hand, you're very likely to play wrong notes (apart from getting tired of course). You just have to make quick arm movements. Not the same muscles are dangerously stretched when, say, you play C-G-C-E-C-G-... without proper arm movement (this results not in wrong notes, but in uneven playing). In this case you have to combine smaller arm movements with good fingerwork to get tensionfree playing. It is similar to a leap in many respects, but not identical.