BlueStacks is a ready built Android emulator. Note that it does not run every Android App and when I tried it out it lagged pretty horribly.
Native Applications are always better choices than emulated. If you use an emulator like BlueStacks, do not expect the same experience as on a dedicated Android device.
There is a lot of android emulators (android SDK, Andy, youwave , genymotion,bluestacks and many more), you can even install android x86 with dual boot
BTW I've heard some rumors that Win10 will let users to run Android app on PC without using third-party software.
Regarding the experience, I think the only difference is the lack of touch gestures (i.e. swipe). According to my personal experience, I think bluestacks and other Android emulators for Windows are most appropriate for playing games. Thus we can enjoy playing favorite Android games on a big screen.