botany vs brushwood

botany and brushwood both are nouns.

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

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

botany (noun)	brushwood (noun)
the branch of biology that studies plants	a dense growth of bushes
all the plant life in a particular region or period	the wood from bushes or small branches