Arm exercise and Physical exercise

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

Physical exercise and arm exercise are semantically related. In some cases you can use "Physical exercise" instead a noun phrase "Arm exercise".

Physical exercise noun - The activity of exerting your muscles in various ways to keep fit.

Arm exercise and physical exercise are semantically related. Sometimes you can replace phrase "Arm exercise" with "Physical exercise", this phrases are similar.