MyLab and Mastering courses are customized with tools and features specific to disciplines and even specific courses, so that one size does not fit all across the many disciplines supported.
Pressbooks is a simple, free book production software. You can use Pressbooks to publish textbooks, syllabi, books and more in multiple formats.
zyBooks are interactive textbook replacements with questions, animations, homework, and embedded coding tool, premised on the idea that STEM students will respond to more interactivity and animation and less texts.