A major difference between books and app is in the tools of their making. The choice of tools and tackles at disposal of developers is simply outrageous. It is obvious that apps have been in vogue for much of the past two decades and there is goldrush in providing whatever the developers need to create apps.
Use vim or emacs if you like the terminal or soak in Sublime or Atom if you prefer a sophisticated text editor. Use a VCS like git or svn to version all history of work and co-author with any number of friends — designers, content writers or developers — anywhere in the world.
Cash in on pull requests from an open community with rapid diff'ing and discussion on forums with like-minded individuals. Apply algorithmic analysis for code quality and perform automated tests. Push to deploy with Capistrano. Ha!
Compare that with what book authors have: MS Word?☺