stratigraphy vs geology

stratigraphy and geology both are nouns.

Word	Noun	Adjective	Verb	Adverb
stratigraphy	Yes	No	No	No
geology	Yes	No	No	No

As nouns, geology is a hypernym of stratigraphy; that is, geology is a word with a broader meaning than stratigraphy:

stratigraphy: the branch of geology that studies the arrangement and succession of strata
geology: a science that deals with the history of the earth as recorded in rocks

stratigraphy (noun)	geology (noun)
the branch of geology that studies the arrangement and succession of strata	a science that deals with the history of the earth as recorded in rocks