tooth decay vs dental caries

tooth decay and dental caries both are nouns.

Word	Noun	Adjective	Verb	Adverb
tooth decay	Yes	No	No	No
dental caries	Yes	No	No	No

As nouns, tooth decay and dental caries are synonyms defined as:

tooth decay and dental caries: soft decayed area in a tooth; progressive decay can lead to the death of a tooth

Other synonyms of tooth decay include caries, cavity.

tooth decay (noun)	dental caries (noun)
soft decayed area in a tooth; progressive decay can lead to the death of a tooth	soft decayed area in a tooth; progressive decay can lead to the death of a tooth