A Primer on OS Process [Operating Systems]

Process Vs Program

Program	Process
Program contains a set of instructions designed to complete a specific task.	Process is an instance of an executing program.
Program is a passive entity as it resides in the secondary memory (to store all instructions).	Process is an active entity as it is created during execution and loaded into the main memory. A process contains memory address which is called address space.
Program is a static entity.	Process is a dynamic entity.
Program does not have any resource requirement, it only requires memory space for storing the instructions.	Process has a high resource requirement, it needs resources like CPU, memory address, I/O during its lifetime.

Characteristic	Multiprogramming	Multiprocessing	Multithreading	Multitasking
What it is:	The concurrent residency of more than one program in the main memory is called as multiprogramming.	The availability of more than one processor per system, which can execute several set of instructions in parallel is called as multiprocessing.	A process is divided into several different sub-processes called as threads, which has its own path of execution. This concept is called as multithreading.	The execution of more than one task simultaneously is called as multitasking.
Number of CPU:	One	More than one	Can be one or more than one	One
Job processing time:	More time is taken to process the jobs.	Less time is taken for job processing.	Moderate amount of time is taken for job processing.	Moderate amount of time.
Number of process being executed:	One process is executed at a time.	More than one process can be executed at a time	Various components of the same process are being executed at a time.	One by one job is being executed at a time.
Economical:	It is economical.	Is less economical.	Is economical.	It is economical.
Number of users:	One at a time.	Can be one or more than one.	Usually one.	More than one.
Throughput:	Throughput is less.	Throughput is maximum.	Moderate.	Throughput is moderate.
Efficiency:	Less	Maximum	Moderate	Moderate
Categories:	No further divisions	Symmetric & Asymmetric.	No further divisions.	Single User & Multiuser.