PMP Prep - Monitor and Control Project Work vs. other control processes

 I wanted to get a clear understanding (with examples) of the difference between the monitor and control project work versus the other control processes. 

For instance, when would the schedule be compared to baseline and a change request be generated? both processes (MCPJ and control schedule)? why two processes?

 

 

 

This is in Integration which is the combined sum or unification of all processes in the Monitor & Controlling Process Management Group.