I. Permission Types can either be "User" or "Admin"
II. Company Roles can be Portfolio Manager, Project Manager, Project Control, Team Member, etc.
III. Access Levels can be "None", "View", "Update"
An Admin is a Super-user that can do all i.e. update User Access levels to (None/View/Update), assign approvers, update role responsibilities etc.
All users Admin or non-admin are assigned Company Roles.
If your Permission is a "User", your access is then set based on your Role, within Company Settings configuration either None, View or Update to modules, projects, portfolios, etc. You can be "Update" access to Projects, but View access to Portfolios, or None to other modules.
If you are an "Admin", it's like an "ALL Update", Super-user access. Regardless if you are None, View, Update within Company Settings, the moment your user is tagged as ADMIN, you can already update anything.
Tip: if your Company Role is ticked/set as "Update" across ALL modules within the Company, it's like an Admin already.