We are often asked what is the difference between a Change and a Release...
A release is simply a large, complex change that may require a significant management into the production environment.
ITIL defines a Change and Release as follows:
Change: The addition, modification or removal of anything that could have an effect on IT services. The scope should include changes to all architectures, processes, tools, metrics and documentation, as well as changes to IT services and other configuration items.
Release: One or more changes to an IT service that are built, tested and deployed together. A single release may include changes to hardware, software, documentation, processes and other components.