Here's where non-standardized meat names is problematic - while a a sirloin tip can be a tri-tip (with ball tip, etc., still attached), it is usually a part of the round.
Top sirloin, is just that, sirloin from the "top" of the animal. It's from the back of the primal, with the shortloin being in the front. The top sirloin is one of the best value steaks out there, great beefy flavor with sufficient tenderness. It's like a poor mans's strip steak...
When I buy dry-aged Prime, it's usually all I can afford, but EXTRA beefy and tender !