botany vs pteridology

botany and pteridology both are nouns.

Word	Noun	Adjective	Verb	Adverb
botany	Yes	No	No	No
pteridology	Yes	No	No	No

As nouns, pteridology is a hyponym of botany; that is, pteridology is a word with a more specific, narrower meaning than botany:

Other hyponyms of botany include mycology, pomology, palaeobotany, paleobotany, algology, phycology.

botany (noun)	pteridology (noun)
the branch of biology that studies plants	the branch of botany that studies ferns
all the plant life in a particular region or period