doubleheader vs double feature

doubleheader and double feature both are nouns.

Word	Noun	Adjective	Verb	Adverb
doubleheader	Yes	No	No	No
double feature	Yes	No	No	No

As nouns, doubleheader and double feature are synonyms defined as:

doubleheader and double feature: two games instead of one (especially in baseball when the same two teams play two games on the same day)

Other synonyms of doubleheader include twin bill.

doubleheader (noun)	double feature (noun)
two games instead of one (especially in baseball when the same two teams play two games on the same day)	two games instead of one (especially in baseball when the same two teams play two games on the same day)