Once upon a time, we would release a software version on a set of removable media (floppy disk, CD, DVD), and customers would deploy (or install) the software on their own systems. So, release means "make available" and deploy means "physically install".
Under Software as a Service (SAAS), we handle deployments on the customer's behalf, so release comes to mean "announce a version" and deploy means "rollout the version to subscribers".
A common Continuous Deployment technique is to "decouple release from deployment". A good example of this kind of decoupling is the Salesforce Critical Update capability. If a change is distributed as a Critical Update, during an introductory period, we can activate and deactivate. Here Salesforce has decoupled "activation from deployment".
As you design a package, a best practice is to "dark launch" new features, and then allow customers to activate a change in their own environment, and also allow yourself to force activation for groups of customers.