Global Epic is not “project bound” and it exists at the company level. Project field value of such Epic is “Global”. Items under such epic can be associated with different projects. Teams use it for defining high-level feature set. Teams using SAFe (Scaled Agile Framework) benefit from Global Epic to maintain their Program level and Value Stream level features.
Project level Epic is commonly used epic to define features of one specific project. With such epic, you can associate only user stories of the same project. To track User Stories of an epic, use Epic board and select the Project name or Global option from the available drop-down projects list. To know Association of each User Story with Project, open global epic in detail view and click on User Stories section.