cayenne pepper vs chilli pepper

cayenne pepper and chilli pepper both are nouns.

Word	Noun	Adjective	Verb	Adverb
cayenne pepper	Yes	No	No	No
chilli pepper	Yes	No	No	No

As nouns, cayenne pepper and chilli pepper are synonyms defined as:

cayenne pepper and chilli pepper: plant bearing very hot and finely tapering long peppers; usually red

Other synonyms of cayenne pepper include Capsicum annuum longum, cayenne, chili pepper, jalapeno, long pepper.

cayenne pepper (noun)	chilli pepper (noun)
ground pods and seeds of pungent red peppers of the genus Capsicum	plant bearing very hot and finely tapering long peppers; usually red
a long and often twisted hot red pepper
plant bearing very hot and finely tapering long peppers; usually red