This course, The Podcaster Ideabook is just that: all about ideas! It doesn't focus on productional at all, and instead helps you turn your idea into a sustainable concept for a podcast.
The Podcaster Playbook focuses entirely on production and works on the assumption that you've already got an idea/concept that you want to turn into a podcast.
Each course serves a different purpose, so not everyone needs both. It's entirely up to you!