sex act vs carnal knowledge

sex act and carnal knowledge both are nouns.

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

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

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

sex act (noun)	carnal knowledge (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