turnip vs turnip plant

turnip and turnip plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
turnip	Yes	No	No	No
turnip plant	Yes	No	No	No

As nouns, turnip plant is a hypernym of turnip; that is, turnip plant is a word with a broader meaning than turnip:

turnip: widely cultivated plant having a large fleshy edible white or yellow root
turnip plant: any of several widely cultivated plants having edible roots

turnip (noun)	turnip plant (noun)
root of any of several members of the mustard family	any of several widely cultivated plants having edible roots
widely cultivated plant having a large fleshy edible white or yellow root