kola nut tree vs nut tree

kola nut tree and nut tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
kola nut tree	Yes	No	No	No
nut tree	Yes	No	No	No

As nouns, nut tree is a hypernym of kola nut tree; that is, nut tree is a word with a broader meaning than kola nut tree:

kola nut tree: tree bearing large brown nuts containing e.g. caffeine; source of cola extract
nut tree: tree bearing edible nuts

kola nut tree (noun)	nut tree (noun)
tree bearing large brown nuts containing e.g. caffeine; source of cola extract	tree bearing edible nuts