By default, Normal is the role given to the new member you have invited. Being a Normal member basically allows you to manage everything in a project, except its members.
An Admin, on the other hand, has all the permissions, including managing a project, and its members.
When you outsource a task to an external team, you can assign different roles to the team’s external members. The external members will only have permissions to the task outsourced to the team even if they take on the Admin role.
For more details, the tables below summarize what each of the four roles can do in a project, organization and external team.