strong belief vs conviction

strong belief and conviction both are nouns.

Word	Noun	Adjective	Verb	Adverb
strong belief	Yes	No	No	No
conviction	Yes	No	No	No

As nouns, strong belief and conviction are synonyms defined as:

strong belief and conviction: an unshakable belief in something without need for proof or evidence

Other synonyms of strong belief include article of faith.

strong belief (noun)	conviction (noun)
an unshakable belief in something without need for proof or evidence	(criminal law) a final judgment of guilty in a criminal case and the punishment that is imposed
	an unshakable belief in something without need for proof or evidence