palaeobotany vs paleobiology

palaeobotany and paleobiology both are nouns.

Word	Noun	Adjective	Verb	Adverb
palaeobotany	Yes	No	No	No
paleobiology	Yes	No	No	No

As nouns, paleobiology is a hypernym of palaeobotany; that is, paleobiology is a word with a broader meaning than palaeobotany:

palaeobotany: the study of fossil plants
paleobiology: a branch of paleontology that deals with the origin and growth and structure of fossil animals and plants as living organisms

Other hypernyms of palaeobotany include botany, phytology, palaeobiology.

palaeobotany (noun)	paleobiology (noun)
the study of fossil plants	a branch of paleontology that deals with the origin and growth and structure of fossil animals and plants as living organisms