What is the difference is usage between <nav> and <menu> in html5?

What is the difference is usage between nav and menu in html5?

nav or menu, which one?

Straight from the horse's mouth:

http://dev.w3.org/html5/spec-author-view/interactive-elements.html#menus

The menu element represents a list of commands.

E.g.:

<menu label="File">
   <button type="button" onclick="fnew()">New...</button>
   <button type="button" onclick="fopen()">Open...</button>
   <button type="button" onclick="fsave()">Save</button>
   <button type="button" onclick="fsaveas()">Save as...</button>
</menu>

http://dev.w3.org/html5/spec-author-view/sections.html#the-nav-element

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.

<nav> is a general section of the site layout that holds navigation content

<menu> is a list of commands within the navigation or any other layout section