Sql Server database or Visual Studio 2015 default database

Question

   I am starting to learn MVC app development. I got references from internet and have been using Visual Studio 2015. I used default template for MVC5 and it have its own database also. I have installed Sql Server 2014 also in my system. So I don't know which one to use as I'm not really getting any clarity on this. Can anybody help? Thanks in advance.