thunderbolt vs bolt of lightning

thunderbolt and bolt of lightning both are nouns.

Word	Noun	Adjective	Verb	Adverb
thunderbolt	Yes	No	No	No
bolt of lightning	Yes	No	No	No

As nouns, thunderbolt and bolt of lightning are synonyms defined as:

thunderbolt and bolt of lightning: a discharge of lightning accompanied by thunder

Other synonyms of thunderbolt include bolt.

thunderbolt (noun)	bolt of lightning (noun)
a shocking surprise	a discharge of lightning accompanied by thunder
a discharge of lightning accompanied by thunder