Difference between 

Emulator (Android) vs Simulator (iOS) 

Simulator (iOS) 

https://help.apple.com/simulator/mac/current/#/deve44b57b2a    Simulator Overview

Use Simulator to rapidly prototype and test builds of your app during the development process. 

Installed as part of the Xcode tools, Simulator runs on your Mac and behaves like a standard Mac app while simulating iPhone, iPad, Apple Watch, or Apple TV environments. 

Each combination of a simulated device and software version is considered its own simulation environment, independent of the others, with its own settings and files. These settings and files exist on every device you test within a simulation environment. Open multiple simulated devices for interactions such as an iPhone and a paired Apple watch.

Use Simulator to:

• Interact with your apps on iOS, watchOS, and tvOS using your pointer and keyboard.

• Prototype and debug your apps.

• Optimize your graphics.

• Test your apps.

Emulator (Android)

https://developer.android.com/studio/run/emulator   Run apps on the Android Emulator

The Android Emulator simulates Android devices on your computer so that you can test your application on a variety of devices and Android API levels without needing to have each physical device.

The emulator provides almost all of the capabilities of a real Android device. You can simulate incoming phone calls and text messages, specify the location of the device, simulate different network speeds, simulate rotation and other hardware sensors, access the Google Play Store, and much more.

Testing your app on the emulator is in some ways faster and easier than doing so on a physical device. For example, you can transfer data faster to the emulator than to a device connected over USB.

The emulator comes with predefined configurations for various Android phone, tablet, Wear OS, and Android TV devices.

Watch the following video for an overview of some emulator features.

You can use the emulator manually through its graphical user interface and programmatically through the command line and the emulator console.  

Simulator                                                                                                                                                                                                                                           Emulator

A system able to mimic another system to a certain degree                     A system that mimics the exact behavior of another system.

May not follow all inherent rules of the system being simulated          Strictly abides by the parameters and rules of the emulated system

Models applications and events Copies behavior of systems