witch hazel vs witch hazel plant

witch hazel and witch hazel plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
witch hazel	Yes	No	No	No
witch hazel plant	Yes	No	No	No

As nouns, witch hazel and witch hazel plant are synonyms defined as:

witch hazel and witch hazel plant: any of several shrubs or trees of the genus Hamamelis; bark yields an astringent lotion

Other synonyms of witch hazel include wych hazel, wych hazel plant.

witch hazel (noun)	witch hazel plant (noun)
lotion consisting of an astringent alcoholic solution containing an extract from the witch hazel plant	any of several shrubs or trees of the genus Hamamelis; bark yields an astringent lotion
any of several shrubs or trees of the genus Hamamelis; bark yields an astringent lotion