lithology vs petrology

lithology and petrology both are nouns.

Word	Noun	Adjective	Verb	Adverb
lithology	Yes	No	No	No
petrology	Yes	No	No	No

As nouns, lithology and petrology are synonyms defined as:

lithology and petrology: the branch of geology that studies rocks: their origin and formation and mineral composition and classification

lithology (noun)	petrology (noun)
the branch of geology that studies rocks: their origin and formation and mineral composition and classification	the branch of geology that studies rocks: their origin and formation and mineral composition and classification