heroism vs gallantry

heroism and gallantry both are nouns.

Word	Noun	Adjective	Verb	Adverb
heroism	Yes	No	No	No
gallantry	Yes	No	No	No

As nouns, heroism and gallantry are synonyms defined as:

heroism and gallantry: the qualities of a hero or heroine; exceptional or heroic courage when facing danger (especially in battle)

Other synonyms of heroism include valiance, valiancy, valor, valorousness, valour.

heroism (noun)	gallantry (noun)
the qualities of a hero or heroine; exceptional or heroic courage when facing danger (especially in battle)	polite attentiveness to women
	the qualities of a hero or heroine; exceptional or heroic courage when facing danger (especially in battle)
	courtesy towards women