writing pad vs message pad

writing pad and message pad both are nouns.

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

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

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

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