gold rush vs windfall

gold rush and windfall both are nouns.

Word	Noun	Adjective	Verb	Adverb
gold rush	Yes	No	No	No
windfall	Yes	No	No	No

As nouns, gold rush and windfall are synonyms defined as:

gold rush and windfall: a sudden happening that brings good fortune (as a sudden opportunity to make money)

Other synonyms of gold rush include bonanza, boom, bunce, godsend, gravy, manna from heaven.

gold rush (noun)	windfall (noun)
a large migration of people to a newly discovered gold field	a sudden happening that brings good fortune (as a sudden opportunity to make money)
a sudden happening that brings good fortune (as a sudden opportunity to make money)	fruit that has fallen from the tree