necking vs petting

necking and petting both are nouns.

Word	Noun	Adjective	Verb	Adverb
necking	Yes	No	No	No
petting	Yes	No	No	No

As nouns, necking and petting are synonyms defined as:

necking and petting: affectionate play (or foreplay without contact with the genital organs)

Other synonyms of necking include caressing, cuddling, fondling, hugging, kissing, smooching, snuggling.

necking (noun)	petting (noun)
affectionate play (or foreplay without contact with the genital organs)	affectionate play (or foreplay without contact with the genital organs)
the molding at the top of a column