sexual relation vs copulation

sexual relation and copulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
sexual relation	Yes	No	No	No
copulation	Yes	No	No	No

As nouns, sexual relation and copulation are synonyms defined as:

sexual relation and copulation: sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur

sexual relation (noun)	copulation (noun)
sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur	sexual activity between individuals, especially the insertion of a man's penis into a woman's vagina until orgasm and ejaculation occur