Yes, they are! We encounter this question quite often in our support tickets and so here's something that will let you differentiate these features and put them to best use.
Going by the standard definition, an epic is a collection of user stories that have to be executed to achieve a particular goal. Release Management helps you to manage the large scale activities of your projects. Epics do not have any time frames but Releases do. Any bigger part of your project that has to release within a specified time will be treated as a release.
XYZ team will be launching two of their customer requests in the upcoming quarter. One would be a Billing module and another would be an Offline Timer in their Timesheet module. Each of these requests, needs an engineering team to implement it, a content team to review the in-app texts and help resources, a UI team and a testing team. All of these need to be managed under one phase, so separate epics will be created for both of these requests and respective user stories and sprints will be tracked. User stories from both of these epics can be added to a release and be released when they're done.
To know about epics and releases in detail, you can check out our help documents. We hope this helps in clarifying the confusion. Do let us know your feedback in the comment section below.
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