drier vs drying agent

drier and drying agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
drier	Yes	No	No	No
drying agent	Yes	No	No	No

As nouns, drier and drying agent are synonyms defined as:

drier and drying agent: a substance that promotes drying (e.g., calcium oxide absorbs water and is used to remove moisture)

Other synonyms of drier include desiccant, siccative.

drier (noun)	drying agent (noun)
an appliance that removes moisture	a substance that promotes drying (e.g., calcium oxide absorbs water and is used to remove moisture)
a substance that promotes drying (e.g., calcium oxide absorbs water and is used to remove moisture)