criminal congress vs unlawful carnal knowledge

criminal congress and unlawful carnal knowledge both are nouns.

Word	Noun	Adjective	Verb	Adverb
criminal congress	Yes	No	No	No
unlawful carnal knowledge	Yes	No	No	No

As nouns, criminal congress and unlawful carnal knowledge are synonyms defined as:

criminal congress and unlawful carnal knowledge: forbidden or tabu sexual intercourse between individuals

criminal congress (noun)	unlawful carnal knowledge (noun)
forbidden or tabu sexual intercourse between individuals	forbidden or tabu sexual intercourse between individuals