Emulator vs Simulator: What Is the Difference?

Both emulators and simulators belong to virtual devices, but there is a significant difference between them. And since this difference affects the way we build a QA process, let’s dive deeper into the topic to investigate all of the pitfalls.

Why Do We Need Virtual Devices?

Effective testing and debugging always precede a successful release. For that purpose, a QA team needs to choose and exploit appropriate device testing solutions. The diversity of testing devices plays a significant role in the QA process because of the numerous operating systems, web browsers, and hardware options that are available today.

It means that testing an application on one smartphone doesn’t guarantee it will function the same way on a different device. To cover the wide range of existing smartphones and tablets, mobile QA specialists can use two kinds of devices – real and virtual.

The benefit of having a real device is obvious: you use exactly the same smartphone your customers will use. How does it work? A software testing company provides its employees with various physical devices. As a rule, these are the most widely used iOS and Android smartphones and tablets. The list of devices should be constantly updated to keep up with the market.

However, it would be too hard and a bit unreasonable to buy all the devices that exist in the world. That’s why virtual testing tools have become an alternative. Cost-effective and very helpful at the early stages of testing, virtual devices come in handy and get their role to play in the software development pipeline.

While real devices do better at the final stages of software testing, just before the release, virtual tools allow testing the essential functionality at the very beginning so that defects don’t pile up later. And in most cases, it is enough for releasing apps without critical bugs.

Do I Emulate Or… Simulate?

So, virtual testing tools such as simulators and emulators are a solution that allows reproducing the functionality of real mobile devices on PCs, mimicking possible end-users’ actions. Both emulators and simulators provide an opportunity to execute software tests and get a quick response. In other words, testing becomes simpler and faster compared to checkups on real hardware.

The question is, are those tools interchangeable? And if not, what is the difference between emulator and simulator in mobile testing? The abovementioned virtual tools do not act the same way. The functionality each of them offers is slightly different, making their purpose different as well.

Emulators in a Nutshell

An emulator is a duplicating system that aims to replicate the functionality of an original system – software + operating system + hardware – using other methods and resources – data transmission protocols, algorithms for performing procedures, and hardware resources.

An emulator can function as a virtual machine of a mobile operating system on a PC. This machine inherits almost all the features and instruments from applications and games running based on iOS, Android, etc. An emulator window is a real smartphone on a PC.

Simulators in a Nutshell

A simulator is a replicating system, and it can imitate only software characteristics and configurations – in other words, internal device performance. Simulators are often used for analyzing, studying, and researching goals. A simulator can imitate some of the end user’s actions, for example, pressing the buttons, running applications, swiping the screen.

The Epic Battle: Emulators vs Simulators

Let’s highlight several essential criteria to analyze and compare the participants:

Usage:

• emulators for software and hardware;
• simulators for internal configurations.

Availability:

• mobile device producers provide both types of devices;
• third-party simulators are also available.

Coding:

• emulators are written in machine-level assembly languages;
• simulators are written in high-level languages.

Test automation: both emulators and simulators are suitable.
Debugging: the task for emulators, but not for simulators.

Performance:

• Emulators’ binary translation makes them slower.
• Simulators are faster compared to emulators.

In practice, Android smartphones are easier to emulate, so simulators are mostly meant for iOS phones. If you haven’t used any virtual devices before, start with the official tools – Android SDK and iOS Simulator (which is a part of Xcode).

Bottom Line

The truth is, emulators mimic real devices very closely, but they will never be a 100% substitute for real device experience. In particular, they cannot reproduce some core features and behaviors, like battery life, camera, interruptions, etc. Simulators don’t consider hardware specifications at all, leaving a QA team unaware of real performance. That’s why it is important for a QA company to have a collection of real devices.

Still, there is no reason to treat the virtual tools as a last resort – keep calm & enjoy virtual tools 😉 The mix of real and virtual devices is the ultimate solution. Use a simulator tool if you have to test interactions with external applications and environments. Use an emulator to check how an app interacts with basic hardware or a mixture of hardware and software. And then, test a software product on some of the most widely used real target devices.