low beam vs shaft of light

low beam and shaft of light both are nouns.

Word	Noun	Adjective	Verb	Adverb
low beam	Yes	No	No	No
shaft of light	Yes	No	No	No

As nouns, shaft of light is a hypernym of low beam; that is, shaft of light is a word with a broader meaning than low beam:

low beam: the beam of a car's headlights that provides illumination for a short distance
shaft of light: a column of light (as from a beacon)

Other hypernyms of low beam include beam, beam of light, irradiation, light beam, ray, ray of light, shaft.

low beam (noun)	shaft of light (noun)
the beam of a car's headlights that provides illumination for a short distance	a column of light (as from a beacon)