sketchbook vs sketch block

sketchbook and sketch block both are nouns.

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

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

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

Other synonyms of sketchbook include sketch pad.

sketchbook (noun)	sketch block (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