chilly vs chili pepper

chilly and chili pepper both are nouns.

Word	Noun	Adjective	Verb	Adverb
chilly	Yes	Yes	No	No
chili pepper	Yes	No	No	No

As nouns, chilly and chili pepper are synonyms defined as:

chilly and chili pepper: very hot and finely tapering pepper of special pungency

Other synonyms of chilly include chile, chili, chilli.

chilly (noun)	chili pepper (noun)
very hot and finely tapering pepper of special pungency	very hot and finely tapering pepper of special pungency
	plant bearing very hot and finely tapering long peppers; usually red

chilly (adjective)	chili pepper (adjective)
appreciably or disagreeably cold
not characterized by emotion
lacking warmth of feeling