What is a release and deployment?

Release

A release is a launch of a specific version of the program (build) for the users.

When you are developing a program, you implement some changes and create new build. This is repeated multiple times until you are satisfied with n-th build and you decide that it could be released to users.

When the build is fully tested and approved for releasing to users, release is prepared and documented. Think about the release as if it was a new version of a product packed and prepared with all the formalities (quality checks, approvals, certificates...), ready to be shipped to users.

Deployment

When the release is prepared, it is just waiting on the shelf to be shipped to users. The shipping process is called deployment. From the technical standpoint the deployment is about copying the newest version to the target environment and installing it there. Once the deployment is finished, the relase is available to users and they can start using it.