Difference between Multiprogramming , Multitasking , Multiprocessing and Multithreading Operating System

Multiprogramming 

In multiprogramming more than one program reside in the main memory. When one job is unable to execute because of I/O operation to complete , it switches to other program and allow that program to run .

As you can see in above figure there are three program in the main memory but only one programming is running(or one program is assigned to CPU) at a time .
The main motive of multiprogramming is to utilize the CPU efficiently.

Multitasking(Time shared)

In multitasking operating system more than one program is assigned to the CPU or switches between the program occurs so fast that it seems like more than one program is running . In multitasking more than program is assigned to CPU at the same time. The main motive of multitasking is to utilize the CPU efficiently and reduce the response time.   

Multiprocessing

In multiprocessing operating system a task is divided between more than one processor(CPU) so that parallelism can be achieved.   

Multithreading

Sometime a program need to do multiple task at the same time. It is an extension of multiprogramming . In multi threading the program is divided into multiple task .