houselights vs light source

houselights and light source both are nouns.

Word	Noun	Adjective	Verb	Adverb
houselights	Yes	No	No	No
light source	Yes	No	No	No

As nouns, light source is a hypernym of houselights; that is, light source is a word with a broader meaning than houselights:

houselights: lights that illuminate the audience's part of a theater or other auditorium
light source: any device serving as a source of illumination

Other hypernyms of houselights include light.

houselights (noun)	light source (noun)
lights that illuminate the audience's part of a theater or other auditorium	any device serving as a source of illumination