white pepper vs Piper nigrum

white pepper and Piper nigrum both are nouns.

Word	Noun	Adjective	Verb	Adverb
white pepper	Yes	No	No	No
Piper nigrum	Yes	No	No	No

As nouns, white pepper and Piper nigrum are synonyms defined as:

white pepper and Piper nigrum: climber having dark red berries (peppercorns) when fully ripe; southern India and Sri Lanka; naturalized in northern Burma and Assam

Other synonyms of white pepper include black pepper, common pepper, Madagascar pepper, pepper.

white pepper (noun)	Piper nigrum (noun)
pepper ground from husked peppercorns	climber having dark red berries (peppercorns) when fully ripe; southern India and Sri Lanka; naturalized in northern Burma and Assam
climber having dark red berries (peppercorns) when fully ripe; southern India and Sri Lanka; naturalized in northern Burma and Assam