bottlebrush buckeye vs buckeye

bottlebrush buckeye and buckeye both are nouns.

Word	Noun	Adjective	Verb	Adverb
bottlebrush buckeye	Yes	No	No	No
buckeye	Yes	No	No	No

As nouns, buckeye is a hypernym of bottlebrush buckeye; that is, buckeye is a word with a broader meaning than bottlebrush buckeye:

bottlebrush buckeye: a spreading shrub with pink flowers; found in southeastern United States
buckeye: tree having palmate leaves and large clusters of white to red flowers followed by brown shiny inedible seeds

Other hypernyms of bottlebrush buckeye include Aesculus hippocastanum, horse chestnut.

bottlebrush buckeye (noun)	buckeye (noun)
a spreading shrub with pink flowers; found in southeastern United States	tree having palmate leaves and large clusters of white to red flowers followed by brown shiny inedible seeds
	the inedible nutlike seed of the horse chestnut