flora vs brier patch

flora and brier patch both are nouns.

Word	Noun	Adjective	Verb	Adverb
flora	Yes	No	No	No
brier patch	Yes	No	No	No

As nouns, brier patch is a hyponym of flora; that is, brier patch is a word with a more specific, narrower meaning than flora:

flora (noun)	brier patch (noun)
(botany) a living organism lacking the power of locomotion	tangled mass of prickly plants
all the plant life in a particular region or period