demonic vs infernal

demonic is not a noun while infernal is a noun.

Word	Noun	Adjective	Verb	Adverb
demonic	No	Yes	No	No
infernal	Yes	Yes	No	No

As adjectives, demonic and infernal are synonyms defined as:

demonic and infernal: extremely evil or cruel; expressive of cruelty or befitting hell

Other synonyms of demonic include diabolic, diabolical, fiendish, hellish, satanic, unholy.

demonic (noun)	infernal (noun)
	an inhabitant of Hell

demonic (adjective)	infernal (adjective)
extremely evil or cruel; expressive of cruelty or befitting hell	being of the underworld
	characteristic of or resembling Hell
	of or pertaining to or characteristic of a very uncontrolled and intense fire
	expletives used informally as intensifiers
	extremely evil or cruel; expressive of cruelty or befitting hell