HTML5 nav element vs. role=“navigation”

Question

Do all of the following carry the same semantic meaning? If not please explain your answer.

1.

Answer 1

WAVE Web Accessibility Tool can be used to get information about things like this.

Though I find the documentation there and the result view when checking a bit confusing. I think it would be good with clear examples since not everyone knows very much about accessibility on the web. (The result view looks very good, but still examples would be helpful.)