hazelnut vs hazelnut tree

hazelnut and hazelnut tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
hazelnut	Yes	No	No	No
hazelnut tree	Yes	No	No	No

As nouns, hazelnut and hazelnut tree are synonyms defined as:

hazelnut and hazelnut tree: any of several shrubs or small trees of the genus Corylus bearing edible nuts enclosed in a leafy husk

Other synonyms of hazelnut include hazel.

hazelnut (noun)	hazelnut tree (noun)
nut of any of several trees of the genus Corylus	any of several shrubs or small trees of the genus Corylus bearing edible nuts enclosed in a leafy husk
any of several shrubs or small trees of the genus Corylus bearing edible nuts enclosed in a leafy husk