petting vs kissing

petting and kissing both are nouns.

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

As nouns, petting and kissing are synonyms defined as:

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

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

petting (noun)	kissing (noun)
affectionate play (or foreplay without contact with the genital organs)	affectionate play (or foreplay without contact with the genital organs)