BeBuilder Blocks and BeBuilder are the same tool. Whatever you create in one is reflected in the other. It's like having 2 builders in 1.
BeBuilder Blocks is a typical backend wireframe editor that allows you to build content easily and quickly using Sections, Wraps and Elements. Design whatever you like and then preview your workflow without page update. Moreover, you can customize your backend editor by using included settings. Decide if you want to have simply view where the content from elements does not appear, on/off hover on elements or fill items with sample content.