sureness vs assurance

sureness and assurance both are nouns.

Word	Noun	Adjective	Verb	Adverb
sureness	Yes	No	No	No
assurance	Yes	No	No	No

As nouns, sureness and assurance are synonyms defined as:

sureness and assurance: freedom from doubt; belief in yourself and your abilities

Other synonyms of sureness include authority, confidence, self-assurance, self-confidence.

sureness (noun)	assurance (noun)
the quality of being steady and unfailing	freedom from doubt; belief in yourself and your abilities
freedom from doubt; belief in yourself and your abilities	a statement intended to inspire confidence
	a binding commitment to do or give or refrain from something
	a British term for some kinds of insurance