demonic vs diabolical

demonic and diabolical both are adjectives.

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

As adjectives, demonic and diabolical are synonyms defined as:

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

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

demonic (adjective)	diabolical (adjective)
extremely evil or cruel; expressive of cruelty or befitting hell	extremely evil or cruel; expressive of cruelty or befitting hell
	showing the cunning or ingenuity or wickedness typical of a devil