petting vs foreplay

petting and foreplay both are nouns.

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

As nouns, foreplay is a hypernym of petting; that is, foreplay is a word with a broader meaning than petting:

petting: affectionate play (or foreplay without contact with the genital organs)
foreplay: mutual sexual fondling prior to sexual intercourse

Other hypernyms of petting include arousal, stimulation.

petting (noun)	foreplay (noun)
affectionate play (or foreplay without contact with the genital organs)	mutual sexual fondling prior to sexual intercourse