magnetic mine vs floating mine

magnetic mine and floating mine both are nouns.

Word	Noun	Adjective	Verb	Adverb
magnetic mine	Yes	No	No	No
floating mine	Yes	No	No	No

As nouns, floating mine is a hypernym of magnetic mine; that is, floating mine is a word with a broader meaning than magnetic mine:

magnetic mine: (nautical) a marine mine that is detonated by a mechanism that responds to magnetic material (as the steel hull of a ship)
floating mine: an explosive mine designed to destroy ships that bump into it

Other hypernyms of magnetic mine include marine mine.

magnetic mine (noun)	floating mine (noun)
(nautical) a marine mine that is detonated by a mechanism that responds to magnetic material (as the steel hull of a ship)	an explosive mine designed to destroy ships that bump into it