Do you guys post the process by which you compile this image anywhere? I was very impressed the last time I saw you put out an update because I have tried in the past (as a learning excercise) to do the exact same thing. Compiling a kernel that supports docker for the pi was quite a challenge. For me, at least.
Not exactly sure where they differ. But the most obvious thing is that Snappy has a completely different way of installing packages and its own package format, too.
HypriotOS on the other hand just uses the standard Debian way of installing and managing software.