mine vs land mine

mine and land mine both are nouns.

Word	Noun	Adjective	Verb	Adverb
mine	Yes	No	Yes	No
land mine	Yes	No	No	No

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

mine: explosive device that explodes on contact; designed to destroy vehicles or ships or to kill or maim personnel
land mine: an explosive mine hidden underground; explodes when stepped on or driven over

Other hyponyms of mine include floating mine, marine mine, booby trap, ground-emplaced mine.

mine (noun)	land mine (noun)
explosive device that explodes on contact; designed to destroy vehicles or ships or to kill or maim personnel	an explosive mine hidden underground; explodes when stepped on or driven over
excavation in the earth from which ores and minerals are extracted

mine (verb)	land mine (verb)
lay mines
get from the earth by excavation