petrology vs geomorphology

petrology and geomorphology both are nouns.

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

As nouns, geomorphology is a hypernym of petrology; that is, geomorphology is a word with a broader meaning than petrology:

petrology: the branch of geology that studies rocks: their origin and formation and mineral composition and classification
geomorphology: the branch of geology that studies the characteristics and configuration and evolution of rocks and land forms

Other hypernyms of petrology include morphology.

petrology (noun)	geomorphology (noun)
the branch of geology that studies rocks: their origin and formation and mineral composition and classification	the branch of geology that studies the characteristics and configuration and evolution of rocks and land forms