Is an operating system an application program?

The operating system itself can be considered application software when performing simple calculating, measuring, rendering, and word processing tasks not used to control hardware via command-line interface or graphical user interface.

What is the difference between an application and an operating system?

The main difference between operating system and application software is that an operating system is a system software that works as the interface between the user and the hardware while the application software is a program that performs a specific task.