Arm exercise and Pull-up

Arm exercise noun - Exercise designed to strengthen the arm muscles.

Pull-up and arm exercise are semantically related. In some cases you can replace phrase "Pull-up" with "Arm exercise", this phrases are similar.

Pull-up noun - An arm exercise performed by pulling yourself up on a horizontal bar until your chin is level with the bar.

Arm exercise and pull-up are semantically related. Sometimes you can use "Arm exercise" instead a noun phrase "Pull-up".