snogging vs caressing

snogging and caressing both are nouns.

Word	Noun	Adjective	Verb	Adverb
snogging	Yes	No	No	No
caressing	Yes	No	No	No

As nouns, caressing is a hypernym of snogging; that is, caressing is a word with a broader meaning than snogging:

snogging: (British informal) cuddle and kiss
caressing: affectionate play (or foreplay without contact with the genital organs)

Other hypernyms of snogging include cuddling, fondling, hugging, kissing, necking, petting, smooching, snuggling.

snogging (noun)	caressing (noun)
(British informal) cuddle and kiss	affectionate play (or foreplay without contact with the genital organs)