1.应用程序编程接口(API)：
API代表应用程序编程接口，它是通信协议和子例程的集合，各种程序使用这些通信协议和子例程在技术产品(例如应用程序和网站)之间进行通信。
2.图形用户界面(GUI)：
GUI代表图形用户界面。它是一个软件平台，允许用户通过视觉指示器表示与电子设备进行交互。
API和GUI之间的区别是：
| S.No. | API | GUI |
|---|---|---|
| 1. | An API permits the communication between two programs. | GUI allows interaction between a human and a computer program. |
| 2. | APIs require high technical skills to leverage. | GUI doesn’t require too much technical know-how or the need to leverage. |
| 3. | API requires back-end storage that is backed by a logical architecture, a library of scripts, and regular management. | GUI requires few resources. |
| 4. | APIs tests are fast in action. | Graphical User Interface tests tend to take longer. |
| 5. | API is cheaper. | GUI is expensive. |
| 6. | API allows the exchange of data through XML or JSON. | GUI doesn’t allows the exchange of data through XML or JSON. |
| 7. | API allows more flexibility when it comes to automation and innovation. | GUI is less flexible when it comes to automation and innovation. |
| 8. | API allows your program to interact with servers. | GUI allows users to interact with your program. |
| 9. | An API is an interface to a library that need use GUI. | Implementing a GUI can involve an API. |
| 10. | Types – Web API, Internal API, Partner API, Open API, etc. | GUI includes Microsoft Windows, macOS, Ubuntu Unity, etc. |