carnal knowledge vs sex act

carnal knowledge and sex act both are nouns.

Word	Noun	Adjective	Verb	Adverb
carnal knowledge	Yes	No	No	No
sex act	Yes	No	No	No

As nouns, carnal knowledge and sex act are synonyms defined as:

carnal knowledge and sex act: 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)	sex act (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