snogging vs smooching

snogging and smooching both are nouns.

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

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

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

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

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