crater vs volcanic crater

crater and volcanic crater both are nouns.

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

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

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

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