I should pull that out from the depths of my “library”
There are combinations. Most “spell books” are normal books with instructions, they may be magically protected, or “weather proofed” etc, but they are just books for the most part.
There are, however, true magical books inscribed with runes, on special paper, with special ink, and when reading these aloud, properly, the runes are invoked, much like they are when engraved. However, there are limits to what you can do with even special paper, particularly if the runes are to be reused.
Then of course, there are certainly runic scrolls, typically these are one time use devices created by Rune Wizards (the oldest type of wizardry), invoking/activating them consumes the scrolls materials which are the material components of the spell. Typically the ink contains whatever herbs, minerals, etc are needed for the spell.
Then of course, there are just normal scrolls. Book binding is not always feasible.