purple vs spectral colour

purple and spectral colour both are nouns.

Word	Noun	Adjective	Verb	Adverb
purple	Yes	Yes	Yes	No
spectral colour	Yes	No	No	No

As nouns, spectral colour is a hypernym of purple; that is, spectral colour is a word with a broader meaning than purple:

Other hypernyms of purple include chromatic color, chromatic colour, spectral color.

purple (noun)	spectral colour (noun)
(Roman Catholic Church) official dress of a cardinal; so named after the Tyrial purple color of the robes	a color that has hue
a color between red and blue
(in ancient Rome) position of imperial status

purple (adjective)	spectral colour (adjective)
of a color intermediate between red and blue
belonging to or befitting a supreme ruler
excessively elaborate or showily expressed

purple (verb)	spectral colour (verb)
color purple
become purple