Emulator & Simulator

Emulator:  

      Emulators are pieces of software that allow an application written for one platform or operating system to be executed on another platform or operating system. For example, Unix emulators running on a windows platform to enable the execution of unix-based programs in a windows based environment.

      In emulator testing, it tests actual production code. It typically reveal many of the same defects as testing on the actual device. It frequently enable test automation, increase test coverage and enable scenario based testing. 

Simulator: 

      Simulators generallly allows users to experience what a thing will look and feel like but which doesn't use the same code base.  For example, a PC-based flight simulators.

      Simulator testing enable testing prior to devices being ready.  It is very good for early testing of user experience or paradigm testing.  It provides all of the benefits of software prototyping, including generation of test ideas. 

Simulator Vs Emulator (Simulations Vs Emulation) : - 

      Simulation is the imitation of another environment. For example, a flight simulator imitates the environment of flying an airplane in a little room. The true environment of flying is experienced in another environment that lacks some aspects like the possibility to die from a plane crash. So, simulation usually involves an environment and a person. Well, if not a person, another object. For example, a savanna simulator may include a lion to see how the lion will react to a certain condition. 

      Emulation is the imitation of an object as another object. For example, a PlayStation emulator makes PlayStation game CDs recognize a PC as the machine where it is intended to run.  

How does an Emulator work :   

Mobile emulators fall into three main categories:

Device emulators - These are generally provided by device manufacturers and simulate the actual device. Device emulators are excellent for testing the site or application on a particular device or set of devices.

Browser emulators - These simulate mobile browser environments. Whilst useful for determining the functionality available in a particular mobile browser, are useless for device-specific testing.

Operating System Emulators - Microsoft provides emulators for Windows Mobile, and Google provides an emulator for Android. These run within a simulated mobile device environment and provide access to applications running within the operating system, e.g. a Web browser.