Let us make it simple and clear. First of all, when you get a smartphone, claim it is an android genuine smartphone, you should check the following:
1.open menu, then go to "market" or sometimes it is written "play store" and open it. This is where all android apps should be downloaded and installed (we know there is other sources such as apk files and root issues, but there are for higher end users, we are not). make sure when you open it for the first time, it ask you either to login with your gmail account or to signup if you dont have.
All fake android devices will not give you this option.
2.brand new original android smartphone doesnot come with apps like facebook, twitter, opera mini and others installed. You have to install them by your self. Many chinesse/fake androids comes with these apps installed, and you can't uninstall them.
These two guidelines will absulutely help you pal. Try them.