Stack Admin vs Stack Developer
The Developer can invite users to a stack and can remove only the users that he/she has invited. The Admin, however, can invite users and can remove any user from the stack.
The Developer role is editable. This means that the default rights assigned to a Developer role can be modified by the Admin, for example, an Admin can assign locale and environment specific access to the Developer. On the other hand, the rights of an Admin role cannot be changed.