light unit vs exposure

light unit and exposure both are nouns.

Word	Noun	Adjective	Verb	Adverb
light unit	Yes	No	No	No
exposure	Yes	No	No	No

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

light unit (noun)	exposure (noun)
a measure of the visible electromagnetic radiation	abandoning without shelter or protection (as by leaving an infant out in the open)
	the act of exposing film to light
	presentation to view in an open or public manner
	the act of subjecting someone to an influencing experience
	a representation of a person or scene in the form of a print or transparent slide or in digital format
	vulnerability to the elements; to the action of heat or cold or wind or rain
	aspect resulting from the direction a building or window faces
	the disclosure of something secret
	the intensity of light falling on a photographic film or plate
	the state of being vulnerable or exposed