What actually is tennis elbow?

Tennis elbow: This is pain that arises from the lateral part of the elbow where the common extensor tendon originates from the lateral epicondyle. Usually arises due to repetitive irritation.

Tendonitis: Tennis elbow is an inflammation at the point of attachment of the muscles that extend your wrist and fingers. This attachment is on the outside of the elbow where the tennis elbow symptoms occur. Primarily, it is a tendonitis, but there can be small tears in the muscular attachment as well. Often, this is a result of repetitive activities.