light brown vs tan

light brown and tan both are nouns.

Word	Noun	Adjective	Verb	Adverb
light brown	Yes	No	No	No
tan	Yes	Yes	Yes	No

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

Other hyponyms of light brown include topaz, dun, fawn, grayish brown, greyish brown, beige, ecru.

light brown (noun)	tan (noun)
a brown that is light but unsaturated	a light brown the color of topaz
	ratio of the opposite to the adjacent side of a right-angled triangle
	a browning of the skin resulting from exposure to the rays of the sun

light brown (adjective)	tan (adjective)
	of a light yellowish-brown color

light brown (verb)	tan (verb)
	get a tan, from wind or sun
	treat skins and hides with tannic acid so as to convert them into leather