Linux – Are there drawbacks when running a different docker base image than my distribution?

My understanding is that the docker image shares the boot filesystem with the host and tries to share as much of the root filesystem as possible.

What happens if I run the Ubuntu base image on my current architecture? They differ not only in the root file system (e.g. systemd vs upstart), but also in the boot file system (e.g. kernels 3.5 vs 3.12). In this case, does the ubuntu image launch its own kernel?

What happens if I run an ubuntu image on Ubuntu?

I should expect:

1. Better performance?
2. Smaller image size?
3. Reduce memory footprint?
4. Is there a low probability of crashes or errors?

If any of these apply: Is it Elixir that creates your own base image for the intended environment?

Docker only shares kernels with the host system. It does not spin new kernels. The full file system is stored in a docker image. You can run only one process in a container instead of the entire system (for example, not running upstart in ubuntu).

I recommend reading this answer related to performance/memory/disk usage, it explains a lot:

What is the impact of using multiple Base Images in Docker?