hallmark vs authentication

hallmark and authentication both are nouns.

Word	Noun	Adjective	Verb	Adverb
hallmark	Yes	No	No	No
authentication	Yes	No	No	No

As nouns, hallmark and authentication are synonyms defined as:

hallmark and authentication: a mark on an article of trade to indicate its origin and authenticity

Other synonyms of hallmark include assay-mark.

hallmark (noun)	authentication (noun)
a distinctive characteristic or attribute of someone or something	validating the authenticity of something or someone
a mark on an article of trade to indicate its origin and authenticity	a mark on an article of trade to indicate its origin and authenticity