blotting paper vs blotter

blotting paper and blotter both are nouns.

Word	Noun	Adjective	Verb	Adverb
blotting paper	Yes	No	No	No
blotter	Yes	No	No	No

As nouns, blotting paper and blotter are synonyms defined as:

blotting paper (noun)	blotter (noun)
absorbent paper used to dry ink	the daily written record of events (as arrests) in a police station
	absorbent paper used to dry ink