fireball vs atomic explosion

fireball and atomic explosion both are nouns.

Word	Noun	Adjective	Verb	Adverb
fireball	Yes	No	No	No
atomic explosion	Yes	No	No	No

fireball (noun)	atomic explosion (noun)
the luminous center of a nuclear explosion	the explosion of an atomic bomb
a ball of fire (such as the sun or a ball-shaped discharge of lightning)
a highly energetic and indefatigable person
an especially luminous meteor (sometimes exploding)