There are two types of changes. One moves forward whereas the other move backward or sideways. (The are not PMI terms. I use them just to help you picture the differences.)
Forward change is normal work as it happens according to plan. You submit the Project Management Plan and ongoing work to CM when they are done and approved by reviewers. The main purpose of CM is to make sure everybody bases new work on the latest, approved plans and work.
CM also provides and controls the repository for work history, process assets, and lessons learned. Once work has been approved and entered into CM, it becomes subject to change control.
Integrated Change Control
Backward changes revise work already done. Sideways work requires changing the Project Management Plan or design plans before moving forward. All changes to the plan or to previous work go through ICC. The ICC procedure ensures that you consider the alternative measures and the effects that a change can have. Passing the change through the ICC Board ensures that people with various perspectives can identify stakeholders and impacts you did not think of. This procedure enables making informed decisions.
The change request and the ICC Board's decision are stored by CM. If the change is approved, the change has to be implemented, and the records of the change (for example, approved, revised documents) are stored by CM. CM usually has responsibility for notifying the stakeholders in accordance with the communications plan.
Think of the ICC as the process for making sure changes to existing plans and work are done the right way. Think of CM as the library where all approved plans and work, including changes, are stored.