The content was static .Now it is interactive. You can go through various routes to learn the things depending on situation. This is same as some novels asking readers to take decisions depending on which there can be varous endings to a story.
Reading books was making sure that you are learning from an expert which meant learning most of the thing. On internet anyone can publish an article very easily and most of the time it is not definitive and are only parts of the topic means it is learning as needed and the content is more personal.
There were less books published and we knew which one are good. If some publisher is publishing any book they might have made sure that it is not crap. On internet there is whole lot of information and there is no one to say about the quality of content. So do we need some more visible rating agency about the content.
Time spent was only on reading the book and buying it. Now most of the time is spent on searching for the information. Specialised portals might be answers.
And the one which in a small way defines the differences till now. Books had a price tag. And in todays world of web 2.0 everything is expected to be free..