film festival vs festival

film festival and festival both are nouns.

Word	Noun	Adjective	Verb	Adverb
film festival	Yes	No	No	No
festival	Yes	No	No	No

As nouns, festival is a hypernym of film festival; that is, festival is a word with a broader meaning than film festival:

film festival: a cinematic festival that features films (usually films produced during the past year)
festival: an organized series of acts and performances (usually in one place)

Other hypernyms of film festival include fete.

film festival (noun)	festival (noun)
a cinematic festival that features films (usually films produced during the past year)	an organized series of acts and performances (usually in one place)
	a day or period of time set aside for feasting and celebration