drying agent vs drier

drying agent and drier both are nouns.

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

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

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

Other synonyms of drying agent include desiccant, siccative.

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