Xray Enterprise helps you design optimized test cases with up to 100% requirements coverage, trigger automated tests, work with dynamic test plans and benefit from an Enterprise Level Support. 

To benefit from Xray Enterprise, you need a valid Xray Standard license.

Xray Enterprise adds the following features to Xray Standard:

• Test Case Designer - Xray Test Case Designer is a revolutionary test design optimization tool that will help increase the effectiveness of your testing.
• Dynamic Test Plans - create test plans based on filters to ensure that you test plan is always up to date.
• Test Case Versioning - with Test Case Versioning users can create different version of the same test case, within the same test issue (without the need to clone the test issue).
• Triggering Remote Jobs -  allows users to trigger pre-configured remote jobs directly from a Test Plan or Test Execution.
• Increased Storage - Storage limit increases to 3TB for Xray Enteprise.

Also with Xray Enterprise, you will have enhanced Support SLA. Check the Xray Enterprise SLA at [Xray] When will my request will be answered by Xray Support? What is the SLA?. 

If you want to learn more about Xray Enterprise please take your free Xray Academy Course  - Xray Enterprise Essentials for Cloud.