French kiss vs deep kiss

French kiss and deep kiss both are nouns.

Word	Noun	Adjective	Verb	Adverb
French kiss	Yes	No	No	No
deep kiss	Yes	No	No	No

As nouns, French kiss and deep kiss are synonyms defined as:

French kiss and deep kiss: an openmouthed kiss in which your tongue is inserted into the other's mouth

Other synonyms of French kiss include soul kiss.

French kiss (noun)	deep kiss (noun)
an openmouthed kiss in which your tongue is inserted into the other's mouth	an openmouthed kiss in which your tongue is inserted into the other's mouth