hazelnut tree vs hazelnut

hazelnut tree and hazelnut both are nouns.

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

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

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

Other synonyms of hazelnut tree include hazel.

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