light beam vs sunbeam

light beam and sunbeam both are nouns.

Word	Noun	Adjective	Verb	Adverb
light beam	Yes	No	No	No
sunbeam	Yes	No	No	No

As nouns, sunbeam is a hyponym of light beam; that is, sunbeam is a word with a more specific, narrower meaning than light beam:

Other hyponyms of light beam include heat ray, high beam, moon-ray, moon ray, moonbeam, sunray, laser beam, low beam.

light beam (noun)	sunbeam (noun)
a column of light (as from a beacon)	a ray of sunlight