think tank vs think factory

think tank and think factory both are nouns.

Word	Noun	Adjective	Verb	Adverb
think tank	Yes	No	No	No
think factory	Yes	No	No	No

As nouns, think tank and think factory are synonyms defined as:

think tank and think factory: a company that does research for hire and issues reports on the implications

think tank (noun)	think factory (noun)
a company that does research for hire and issues reports on the implications	a company that does research for hire and issues reports on the implications