long pepper vs cayenne

long pepper and cayenne both are nouns.

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

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

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

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

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