Owner is a role for Azure Resources entities (Subscriptions/Resource Groups/VMs/...) and Global Administrator is a role for Azure AD entities (Users/Users groups/Applications/...).
I think, you can say that each Azure subscription can have multiple owners.
You can read more about this at:
https://learn.microsoft.com/en-us/azure/role-based-access-control/rbac-and-directory-admin-roles
Hope this helps.