sweet pepper plant vs pimiento

sweet pepper plant and pimiento both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweet pepper plant	Yes	No	No	No
pimiento	Yes	No	No	No

As nouns, sweet pepper plant and pimiento are synonyms defined as:

sweet pepper plant and pimiento: plant bearing large mild thick-walled usually bell-shaped fruits; the principal salad peppers

Other synonyms of sweet pepper plant include bell pepper, Capsicum annuum grossum, paprika, pimento, sweet pepper.

sweet pepper plant (noun)	pimiento (noun)
plant bearing large mild thick-walled usually bell-shaped fruits; the principal salad peppers	fully ripened sweet red pepper; usually cooked
	plant bearing large mild thick-walled usually bell-shaped fruits; the principal salad peppers