Operation System OS-An operation system is a set of program s that

coordinate all the activities among the computer hardware devices.
-In most cases, the OS is installed and resides on the computer hard disk.
-However, an handheld computer and many mobile devices such as PDA’s and Smart Phones, the OS mary resides on a ROM Chip.
-The OS that a computer uses sometimes is called the platform.

Utility Program

A utility program which is also called a utility is a type of system software that allows a user to perform maintenence type task usually related to managing a computer, its devices or its program.