positive vs certain

positive is a noun but certain is not a noun.

Word	Noun	Adjective	Verb	Adverb
positive	Yes	Yes	No	No
certain	No	Yes	No	No

positive (noun)	certain (noun)
a film showing a photographic image whose tones correspond to those of the original subject
the primary form of an adjective or adverb; denotes a quality without qualification, comparison, or relation to increase or diminution

positive (adjective)	certain (adjective)
characterized by or displaying affirmation or acceptance or certainty etc.	established beyond doubt or question; definitely known
indicating existence or presence of a suspected condition or pathogen	having or feeling no doubt or uncertainty; confident and assured
reckoned, situated or tending in the direction which naturally or arbitrarily is taken to indicate increase or progress or onward motion	certain to occur; destined or inevitable
of or relating to positivism	established irrevocably
involving advantage or good	exercising or taking care great enough to bring assurance
persuaded of; very sure	definite but not specified or identified
having a positive charge	reliable in operation or effect
marked by excessive confidence
formally laid down or imposed
greater than zero
impossible to deny or disprove