crater vs lunar crater

crater and lunar crater both are nouns.

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

As nouns, lunar crater is a hyponym of crater; that is, lunar crater is a word with a more specific, narrower meaning than crater:

crater: a bowl-shaped depression formed by the impact of a meteorite or bomb
lunar crater: a crater on the Earth's Moon

Other hyponyms of crater include collector.

crater (noun)	lunar crater (noun)
a bowl-shaped depression formed by the impact of a meteorite or bomb	a crater on the Earth's Moon
a bowl-shaped geological formation at the top of a volcano