Where is the admin center?

Hello,

I'm new in SharePoint 2013 (experience with SharePoint 2010).  When I'm looking in the documentation and search on the internet, in the top menu bar, I can see 'admin' and 'sharepoint'.  But I don't have these possibility in my local sharepoint.  

• What's the difference? 
• How to enable this?

Greetings and thanks for helping me,

Steven