I am halfway through an online degree in ICT. We had a Instructional Design course that went over the differences. There is a textbook that has a chapter on it called Trends in Instructional Design but it is pricey. My position is adult learning works better online to reorganize cognitive schemas but children benefit from social learning theory. It is something like 1-5% complete MOOCs, they really need some kind of personal feedback. But generative AI may change this too. Look at Math Academy for example (Skycak has a book about it) (and they don't use gen AI for the tutoring either). https://www.justinmath.com/books/