One of the differences between iOS and Android is the ability to Root the Android device.
This allows the user to access the boot loader, custom recovery and change many aspects of the software.
This prezi is a very brief explanation of two of the things I personally have changed on my phone using the Root access privileges.
Before you find out how to Root your Android DO YOUR RESEARCH. In the process of rooting and making changes to my phone I lost a lot of data. BACK UP YOU PHONE BEFORE YOU TRY ANYTHING. You can permanently damage your phone if you make mistakes. Read about Boot loops and find out how to fix one if you get one.
There are hundreds of Rooting for tutorials so just look up you phone and make sure its compatible with your current version of Android.
Here are some sources and useful links:
Rooting Tutorials www.androidcentral.com/root
Custom Kernels http://www.makeuseof.com/tag/consider-using-custom-android-kernel/
10 reasons to root your phone http://www.techlife.net/2014/07/10-best-reasons-to-root-android-phones.html/