vicious cycle vs vicious circle

vicious cycle and vicious circle both are nouns.

Word	Noun	Adjective	Verb	Adverb
vicious cycle	Yes	No	No	No
vicious circle	Yes	No	No	No

As nouns, vicious cycle and vicious circle are synonyms defined as:

vicious cycle and vicious circle: one trouble leads to another that aggravates the first

vicious cycle (noun)	vicious circle (noun)
one trouble leads to another that aggravates the first	an argument that assumes that which is to be proved
	one trouble leads to another that aggravates the first