filmdom vs film industry

filmdom and film industry both are nouns.

Word	Noun	Adjective	Verb	Adverb
filmdom	Yes	No	No	No
film industry	Yes	No	No	No

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

filmdom: the personnel of the film industry
film industry: the entertainment industries involved in producing and distributing movies

Other hypernyms of filmdom include movie industry.

filmdom (noun)	film industry (noun)
the personnel of the film industry	the entertainment industries involved in producing and distributing movies