luminance unit vs ft-L

luminance unit and ft-L both are nouns.

Word	Noun	Adjective	Verb	Adverb
luminance unit	Yes	No	No	No
ft-L	Yes	No	No	No

As nouns, ft-L is a hyponym of luminance unit; that is, ft-L is a word with a more specific, narrower meaning than luminance unit:

Other hyponyms of luminance unit include nit, foot-lambert.

luminance unit (noun)	ft-L (noun)
a measure of luminance	a former luminance unit equal to one lumen per square foot