Field artillery and Heavy weapon

Field artillery noun - Movable artillery (other than antiaircraft) used by armies in the field (especially for direct support of front-line troops).

Heavy weapon and field artillery are semantically related. In some cases you can use "Heavy weapon" instead a noun phrase "Field artillery".

Heavy weapon noun - Large but transportable armament.

Field artillery and heavy weapon are semantically related. Sometimes you can replace phrase "Field artillery" with "Heavy weapon", this phrases are similar.