pluton vs igneous rock

pluton and igneous rock both are nouns.

Word	Noun	Adjective	Verb	Adverb
pluton	Yes	No	No	No
igneous rock	Yes	No	No	No

As nouns, igneous rock is a hypernym of pluton; that is, igneous rock is a word with a broader meaning than pluton:

pluton: large mass of intrusive igneous rock believed to have solidified deep within the earth
igneous rock: rock formed by the solidification of molten magma

pluton (noun)	igneous rock (noun)
large mass of intrusive igneous rock believed to have solidified deep within the earth	rock formed by the solidification of molten magma