intimacy vs sexual relationship

intimacy and sexual relationship both are nouns.

Word	Noun	Adjective	Verb	Adverb
intimacy	Yes	No	No	No
sexual relationship	Yes	No	No	No

As nouns, sexual relationship is a hypernym of intimacy; that is, sexual relationship is a word with a broader meaning than intimacy:

intimacy (noun)	sexual relationship (noun)
close or warm friendship	a relationship involving sexual intimacy
a feeling of being intimate and belonging together
a usually secretive or illicit sexual relationship