necking vs sexual activity

necking and sexual activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
necking	Yes	No	No	No
sexual activity	Yes	No	No	No

necking (noun)	sexual activity (noun)
affectionate play (or foreplay without contact with the genital organs)	activities associated with sexual intercourse
the molding at the top of a column