Continuous Delivery means you build software in such a way that it can be released to production at any time| martinfowler.com
Blue-green deployment allows you to upgrade production software without downtime. You deploy the new version into a copy of the production environment and change routing to switch.| martinfowler.com
A canary release occurs when you roll out a new version of some software to a small subset of your user base to see if there are any problems before you make it available to everyone.| martinfowler.com