brier patch vs vegetation

brier patch and vegetation both are nouns.

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

As nouns, vegetation is a hypernym of brier patch; that is, vegetation is a word with a broader meaning than brier patch:

Other hypernyms of brier patch include botany, flora.

brier patch (noun)	vegetation (noun)
tangled mass of prickly plants	inactivity that is passive and monotonous, comparable to the inactivity of plant life
	an abnormal growth or excrescence (especially a warty excrescence on the valves of the heart)
	all the plant life in a particular region or period
	the process of growth in plants