Emulators vs Simulators: What’s the Difference

Releasing software without rigorous testing can cause unstable performance for consumers due to the potential for bugs and glitches. Simulators and emulators are two methods of virtual testing that allows developers to test their product without a physical device.

Simulators re-create the virtual space which allows external communication between different software. Emulators re-create the hardware parameters of real devices to test the internal communication of the software with hardware components of the device.

This article will explain the differences between the two modes of virtual testing: simulators, and emulators. It will touch on the differences in the degree of re-implementation, speed, purpose, and compatibility between simulators and emulators.

Virtual Testing

There are two methods for testing device software: real device testing and virtual testing. Real device testing can test the actual performance of device software on specific devices. It provides real-time software performance data and is usually done before releasing the software to the consumers.

However, real device testing requires the physical devices in order to test the software. Real device testing can be costly for software developers and can increase the cost of software production dramatically. 

Virtual testing is a much cheaper and more efficient way of testing software across various brands and device hardware. It is also faster to execute with significantly low error rates in relation to sample size.

Virtual testing works by mimicking devices in a virtual environment to test software. It provides software developers with a clear perspective on how the software will perform given the particular specifications of a device. 

Mimicking, however, does not guarantee actual device performance. As such, the accuracy and reliability of virtual device testing is still considered inferior when compared to actual device testing. Still, the difference is offset with the ability of virtual testing to conduct software tests across a wide spectrum of devices without incurring large costs.

Emulators and simulators are the two types of virtual testing software. These two modes of virtual testing allow software developers to test the product by adjusting virtual software parameters to mimic specific devices. The difference between these two modes of virtual testing lies in the incorporation of hardware.  

Simulators vs Emulators

Simulators are composed of mathematical formulations that attempt to create a virtual space where software developers can analyze the behavior of the product when introduced with a specific stimulus. It also contains the common variables that exist in the actual user environment to check if the software responds appropriately to user commands/input. 

Simulators, however, only test software-to-software engagement. It does not attempt to mimic the actual device hardware that powers and runs the device software.

Emulators mimic both the hardware and the software. It recognizes the role of understanding hardware in the actual performance of the software for the end-user. It is the closest replication of real device testing.

emulators vs simulators
Slippi.gg/Dolphin Emulator

Emulators mimic software and hardware using assembly language. IBM first conceived the idea to create a software emulator to allow newer devices to run older software created for older or different devices. Today, it is often used to run video games from previous generations of gaming platforms on newer and more powerful devices. 

In terms of software testing, emulators should not be used as a substitute for real device testing. Despite mimicking software and hardware at the same time, its ability to mimic only provides deep insight for the developers to predict software behavior following specific hardware and software parameters. 

Degree of Re-Implementation

Simulators only simulate software performance based on software parameters. It does not include hardware performance in the factors that can affect software performance. As such, it only serves as partial re-implementation of the actual software and is usually done in the initial stages of software development to check responsiveness when interacting with other software products. 

Emulators execute a complete re-implementation by incorporating hardware performance in running software. It attempts to test or run software using the final form of actual devices where hardware impacts software performance. 

Emulators are often used during the final stages of software development as a secondary solution to real device testing. It contains additional parameters that allow users to tweak hardware performance to test the software across various hardware components. 


Software developers often use simulators to test the cross-software behavior of a particular product. Usually, this involves the interaction of their software with web browsing applications to ensure a seamless transition and sending of data from one software to another. Cross-software interaction and communication hardly require any hardware intervention which makes simulators ideal for this type of testing. 

Simulators are also best used for troubleshooting software and application. A lot of software crashes occur because of mistakes in coding which prevents one software from communicating with another without error. This also does not require hardware intervention, making it ideal for software testing. 

Emulators are best used for testing software appearance and responsiveness in various device displays. This ensures the correct developer-intended interface between the software and the device screen.

It also helps to speed up the debugging process. While simulators can be used for troubleshooting and finding errors in coding known as “bugs”, the debugging process or the process of finding and resolving bugs is best reserved for emulators.

An emulator can duplicate the performance of specific devices and can run the software according to the emulator-defined hardware parameters. This prevents software developers from switching across devices to debug an application for a particular device. 

Simulators are best used during the start of the development cycle due to its capability to replicate software performance and cross-software interaction. Emulators, on the other hand, are best used towards the end of the software development process to test the end product against actual hardware parameters and prevent software defects for end users. 


Emulators are usually slower than simulators when testing software. It requires cross-platform binary translation of Instruction Set Architecture (ISA) from one device to the ISA of a computer.

ISA is an instruction set created through machine language which requires binary translation to allow the computer to duplicate the performance of the target device. The required translation to emulate device performance comes with latency. 

The latency comes from the real-time translation of instruction that the emulator receives from the user to execute a software command. Simulators don’t have this latency because it does not require binary translation when executing commands. 

Usually, emulators underperform when compared with the actual devices due to binary translation. However, it can also exceed the original device‚Äôs performance when given computer hardware that can process the translation at high speeds. It can even add supplementary features that are not present on the actual device. 

External vs Internal Environment

Simulators are best for testing the external behavior of the software while emulators are best used to assessing internal behavior.

The external behavior of the application refers to its ability to communicate and interface with external software such as web browsers. Internal behavior refers to the software interface with the device hardware. 

Simulators are often referred to as testing the software in isolation with the device. Where-as emulators work with their environment, particularly its hardware, in testing software viability. These are essential differences between emulators and simulators that determine their utilization in different aspects of software testing. 


In terms of compatibility, simulators are platform-specific. Programs that are built on a different operating system (OS) can have difficulty running in a simulator. As such, iOS software applications require simulators that run on the native cocoa API that is present on Apple devices and computers.

Emulators can test on a wide range of OS and devices. It rarely has compatibility issues with software built on different OS. As such, emulators are often used for the digital preservation of older software technologies. 

Final Thoughts

Simulators and emulators are both effective means for virtual testing that can help to troubleshoot software depending on the type of problems being encountered.

Simulators are best used during the early stages of the software development process to help ensure seamless software-to-software external interface.

Emulators are used in more varied ways and are more popular today for debugging, digital preservation, and playing older titles on newer devices.

About the author

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David Marshall

David follows the latest computer hardware trends: CPUs, GPUs, RAM, SSDs/HDDs, Mobos, CPU Coolers, and more. While some people may enjoy building birdhouses or model planes on their weekends, David opts to build and customize gaming rigs.