The Main Idea is that they're all trying to get out of Boneville and back to their homes
The. plot is that as they're all tying to leave, they run into many problems. Such as fat creatures, dragons, and people trying to stop them.
The characters are basically just the Bone cousins.
Similarities and Differences:
In all the other Bones, the Bone cousins were just in Boneville. But now they want to leave. A similarity is that they're still fighting against most of the same characters.