Lately hearing a lot about Android launchers and you have no idea what they are. Android is open source and each developer ships unique and different looking Android. Check of the pictures below.
Check the screens, on the right is LG Touch Wiz and on right is HTC Sense. Both are Android but look completely different. Both companies have customized the interface of their phones but having the same core in the background. Its like the same drink but with different packaging. These customization are possible due to launchers. These launchers are place from which you access various features of your phone and launch apps.