Devil vs Beelzebub

Devil and Beelzebub both are nouns.

Word	Noun	Adjective	Verb	Adverb
Devil	Yes	No	No	No
Beelzebub	Yes	No	No	No

As nouns, Devil and Beelzebub are synonyms defined as:

Devil and Beelzebub: (Judeo-Christian and Islamic religions) chief spirit of evil and adversary of God; tempter of mankind; master of Hell

Other synonyms of Devil include Lucifer, Old Nick, Prince of Darkness, Satan, the Tempter.

Devil (noun)	Beelzebub (noun)
(Judeo-Christian and Islamic religions) chief spirit of evil and adversary of God; tempter of mankind; master of Hell	(Judeo-Christian and Islamic religions) chief spirit of evil and adversary of God; tempter of mankind; master of Hell