The subprocess module lets you run and control other programs. Anything you can start with the command line on the computer, can be run and controlled with this module. Use this to integrate external programs into your Python code.

The multiprocessing module lets you divide tasks written in python over multiple processes to help improve performance. It provides an API very similar to the threading module; it provides methods to share data across the processes it creates, and makes the task of managing multiple processes to run Python code (much) easier. In other words, multiprocessing lets you take advantage of multiple processes to get your tasks done faster by executing code in parallel.