The two different change control mechanisms in the implementation phase are:
The system or application is moved from development status to production status by installation, deployment, roll out, and testing of the newly installed system or application. To sum it all up, this phase is used to deploy and enable operations of the system in the environment securely or under controlled circumstances in case of errors or changes needed in the software.
These are the two main control mechanisms in this phase:
1) System deployment
2) Training on the system
Hope this helps, I am not an expert at this, but please feel free to ask me a follow up question if needed. have a good day