grenadier vs foot soldier

grenadier and foot soldier both are nouns.

Word	Noun	Adjective	Verb	Adverb
grenadier	Yes	No	No	No
foot soldier	Yes	No	No	No

As nouns, foot soldier is a hypernym of grenadier; that is, foot soldier is a word with a broader meaning than grenadier:

Other hypernyms of grenadier include footslogger, infantryman, marcher.

grenadier (noun)	foot soldier (noun)
deep-sea fish with a large head and body and long tapering tail	fights on foot with small arms
an infantryman equipped with grenades	an assistant subject to the authority or control of another