Release notes are documents that are distributed with software products, sometimes when product is still in development or test state (e.g. a beta release). For products that have already been in use by clients, the release note is delivered to the customer when an update is released.
Release notes are documents that are shared with end users, customers and clients of an organization. They detail the corrections, changes or enhancements made to the service or product the company provides. This document is usually circulated only after product or service is thoroughly tested and approved against specification provided by the development team.