end of the world vs doom

end of the world and doom both are nouns.

Word	Noun	Adjective	Verb	Adverb
end of the world	Yes	No	No	No
doom	Yes	No	Yes	No

As nouns, end of the world and doom are synonyms defined as:

Other synonyms of end of the world include day of reckoning, doomsday.

end of the world (noun)	doom (noun)
an unpleasant or disastrous destiny	an unpleasant or disastrous destiny
(New Testament) day at the end of time following Armageddon when God will decree the fates of all individual humans according to the good and evil of their earthly lives

end of the world (verb)	doom (verb)
	pronounce a sentence on (somebody) in a court of law
	decree or designate beforehand
	make certain of the failure or destruction of