How do you define a Release Manager v/s a Change Manager?

Before I say anything about these roles, keep in mind that these two roles can be and often are combined in smaller organizations. As per the ITIL definitions the Release Manager (RM) gets involved at Service Transition and stays involved to the end from then. The Change Manager (ChM) gets involved in all phases starting at the Service Strategy phase onwards. From the Service Transition phase onwards their roles pretty much overlap. The big difference is that a pure ChM should never actually be writing the deployment scripts and deploying.


The RM's focus is the planning of the Releases and creating a single or multiple Releases from all the changes being implemented at any given time. The RM gets involved as soon as a Change is being planned with an implementation date. The RM gets involved from Service Transition to Service Operation to Continual Service Improvement. The RM often is actually involved in the deployment and can also write the build and deploy scripts if that is needed.


The Change Manager gets involved a lot earlier in the process. The ChM's focus is the full life-cycle including the lessons learned to assist in increasing the success rate of changes in the future. 


In conclusion, the RM is more in the weeds of the Change and may need to be more technical (scripting, tools expertise for deploying, etc.), while the ChM has a relatively higher level view of the Change.  The ChM gets the involvement of the end-user if possible (business end of the company/sample customer etc.)