message pad vs writing pad

message pad and writing pad both are nouns.

Word	Noun	Adjective	Verb	Adverb
message pad	Yes	No	No	No
writing pad	Yes	No	No	No

As nouns, message pad and writing pad are synonyms defined as:

message pad and writing pad: a pad of paper on which messages can be written

message pad (noun)	writing pad (noun)
a pad of paper on which messages can be written	a pad of paper on which messages can be written