sketch block vs sketch pad

sketch block and sketch pad both are nouns.

Word	Noun	Adjective	Verb	Adverb
sketch block	Yes	No	No	No
sketch pad	Yes	No	No	No

As nouns, sketch block and sketch pad are synonyms defined as:

sketch block and sketch pad: a book containing sheets of paper on which sketches can be drawn

Other synonyms of sketch block include sketchbook.

sketch block (noun)	sketch pad (noun)
a book containing sheets of paper on which sketches can be drawn	a book containing sheets of paper on which sketches can be drawn