carnal knowledge vs coitus

carnal knowledge and coitus both are nouns.

Word	Noun	Adjective	Verb	Adverb
carnal knowledge	Yes	No	No	No
coitus	Yes	No	No	No

As nouns, carnal knowledge and coitus are synonyms defined as:

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

carnal knowledge (noun)	coitus (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