efficiency vs ratio

efficiency and ratio both are nouns.

Word	Noun	Adjective	Verb	Adverb
efficiency	Yes	No	No	No
ratio	Yes	No	No	No

As nouns, ratio is a hypernym of efficiency; that is, ratio is a word with a broader meaning than efficiency:

efficiency: the ratio of the output to the input of any system
ratio: the relative magnitudes of two quantities (usually expressed as a quotient)

efficiency (noun)	ratio (noun)
skillfulness in avoiding wasted time and effort	the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree
the ratio of the output to the input of any system	the relative magnitudes of two quantities (usually expressed as a quotient)