What is the difference between suexec and apache2-mpm-itk?

Question

Apache HTTP Server

I have suexec. Came across information about apache2-mpm-itk. And I had a question, do I need to install it if I already have suexec? And if so, for what? What is the difference between them?
And in the appendage, if not difficult, can you tell me what to pay attention to for safety. I know a lot of information, but I'm already tired of re-reading the same thing, and everywhere something is missing. I would like to have everything in one place.