brightness vs physical property

brightness and physical property both are nouns.

Word	Noun	Adjective	Verb	Adverb
brightness	Yes	No	No	No
physical property	Yes	No	No	No

As nouns, physical property is a hypernym of brightness; that is, physical property is a word with a broader meaning than brightness:

brightness: the quality of being luminous; emitting or reflecting light
physical property: any property used to characterize matter and energy and their interactions

brightness (noun)	physical property (noun)
the location of a visual perception along a continuum from black to white	any property used to characterize matter and energy and their interactions
the quality of being luminous; emitting or reflecting light
intelligence as manifested in being quick and witty