Docker question. How docker create and docker run commands work?

Question

Docker

The essence of the question is this:
1) What does the docker create ubuntu command do?
--- Just creates a layered file system over the existing image or what?
2) What does the docker run command do?
--- Does it actually create its own layer over the existing image + launches the docker image?
3) And what is the docker start command for?
---Does it just start a stopped container ?

Answer 1

1) What does the docker create ubuntu command do?

Unpacks the image and creates a container based on it
Unpacks the image and creates a container based on it and runs it
Runs a previously created container