Project admins also have access to a subset of the Admin section. They can manage projects, fields, statues, configurations etc. (all sections grouped under the Management section of the Admin area). This is useful if you want to grant limited admin access to some project managers, for example. Important: project admins can still do a lot of damage to your configuration, as they have full access to manage (and delete) custom fields, integrations, workflows etc. So make sure to only assign this user type to users who know what they are doing.