Hi all, I’ve installed BlueStacks emulator for android apps, is it means that if the app running on emulator, it also will run on the actual devices too?
You can create an app that only runs in emulator 
But yeah, if your app starts fine with emulator, it should start up with actual device. Performance is an another story.
On a fairly standard-issue gaming rig (3ghz CPU, decent graphics card) the performance of your Unity game in Bluestacks will be pretty amazing, far faster than on a device and at least 10x faster than the Google android emulator when emulating an Arm processor. Once Unity finally supports x86 Android this will be less of an issue as you’d be able to use the x86 android emulator with Intel HAXM acceleration.
In the meantime, for more detailed testing Bluestacks might not suit you because AFAIK it:-
a) doesn’t support multi touch input devices
b) only has limited gamepad support (which works by mapping gamepad inputs to touches via an .ini file)
c) doesn’t allow bridged networking (e.g. for testing multiplayer).
I’ve been testing a new emulator called Genymotion (www.genymotion.com) but at the moment it is very buggy with Unity games. It does, however, such a huge amount of promise as is really fast and flexible.
Kind regards
Dave