volcanic crater vs crater

volcanic crater and crater both are nouns.

Word	Noun	Adjective	Verb	Adverb
volcanic crater	Yes	No	No	No
crater	Yes	No	No	No

As nouns, volcanic crater and crater are synonyms defined as:

volcanic crater and crater: a bowl-shaped geological formation at the top of a volcano

volcanic crater (noun)	crater (noun)
a bowl-shaped geological formation at the top of a volcano	a bowl-shaped depression formed by the impact of a meteorite or bomb
	a bowl-shaped geological formation at the top of a volcano