paleobotany vs palaeobiology

paleobotany and palaeobiology both are nouns.

Word	Noun	Adjective	Verb	Adverb
paleobotany	Yes	No	No	No
palaeobiology	Yes	No	No	No

As nouns, palaeobiology is a hypernym of paleobotany; that is, palaeobiology is a word with a broader meaning than paleobotany:

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

Other hypernyms of paleobotany include botany, phytology, paleobiology.

paleobotany (noun)	palaeobiology (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