scale down vs proportion

scale down is not a noun while proportion is a noun.

Word	Noun	Adjective	Verb	Adverb
scale down	No	No	Yes	No
proportion	Yes	No	Yes	No

As verbs, proportion is a hypernym of scale down; that is, proportion is a word with a broader meaning than scale down:

Other hypernyms of scale down include rescale.

scale down (noun)	proportion (noun)
	magnitude or extent
	harmonious arrangement or relation of parts or elements within a whole (as in a design)
	the quotient obtained when the magnitude of a part is divided by the magnitude of the whole
	the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree
	balance among the parts of something

scale down (verb)	proportion (verb)
reduce proportionally	adjust in size relative to other things
make smaller	give pleasant proportions to