Android UX – when to use Tabs and when to use Navigation Drawer?

I'm looking for guidelines regarding when to use Tabs vs. when to use a Navigation Drawer(sidebar).

For example, as of these days, Facebook and Dropbox, which are extremely popular (+100M users), use tabs and do NOT use the sidebar. See screenshots below.

Many other Android apps, including Google's, do use the sidebar.

It feels like both tabs and the sidebar belong to the same navigation concept but have a different implementation.

So, If my app includes 3-4 main views, what should I use? Tabs or Sidebar?

Thanks.