Assault rifle and Machine rifle

Assault rifle noun - Any of the automatic rifles or semiautomatic rifles with large magazines designed for military use.

Machine rifle and assault rifle are semantically related. In some cases you can use "Machine rifle" instead a noun phrase "Assault rifle".

Machine rifle noun - Light machine gun.

Assault rifle and machine rifle are semantically related. Sometimes you can replace phrase "Assault rifle" with "Machine rifle", this phrases are similar.