[gjulianm]

It does not make too much sense to compare textbooks and class notes, specially when you get to higher level classes where the textbooks are reference textbooks, hardly readable by someone who is not already familiar with the material.

Your study notes will contain parts of the textbook, of course, but also explanations that are not in the book, maybe examples that you find useful and that might not be in the book, counterexamples, doubts, schematics... No textbook will have 100% of the contents you need to study.