legionnaire vs soldier

legionnaire and soldier both are nouns.

Word	Noun	Adjective	Verb	Adverb
legionnaire	Yes	No	No	No
soldier	Yes	No	Yes	No

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

legionnaire: a soldier who is a member of a legion (especially the French Foreign Legion)
soldier: an enlisted man or woman who serves in an army

legionnaire (noun)	soldier (noun)
a soldier who is a member of a legion (especially the French Foreign Legion)	a wingless sterile ant or termite having a large head and powerful jaws adapted for defending the colony
	an enlisted man or woman who serves in an army

legionnaire (verb)	soldier (verb)
	serve as a soldier in the military