casebook vs textbook

casebook and textbook both are nouns.

Word	Noun	Adjective	Verb	Adverb
casebook	Yes	Yes	No	No
textbook	Yes	Yes	No	No

As adjectives, casebook and textbook are synonyms defined as:

casebook and textbook: according to or characteristic of a casebook or textbook; typical

casebook (noun)	textbook (noun)
a book in which detailed written records of a case are kept and which are a source of information for subsequent work	a book prepared for use in schools or colleges

casebook (adjective)	textbook (adjective)
according to or characteristic of a casebook or textbook; typical	according to or characteristic of a casebook or textbook; typical