pallor vs skin colour

pallor and skin colour both are nouns.

Word	Noun	Adjective	Verb	Adverb
pallor	Yes	No	No	No
skin colour	Yes	No	No	No

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

pallor: unnatural lack of color in the skin (as from bruising or sickness or emotional distress)
skin colour: the coloring of a person's face

Other hypernyms of pallor include complexion, skin color.

pallor (noun)	skin colour (noun)
unnatural lack of color in the skin (as from bruising or sickness or emotional distress)	the coloring of a person's face