Notified admins receive a notification for every incoming request. This notification is informative and does not prompt them to perform an action. All notified budget admins are members of the umbrella portal with the Manage permission for budget requests.
Reviewers receive a notification for incoming requests that satisfy their applied rules. This notification prompts them to approve or deny the contents of the budget request. Budget reviewers are not necessarily associated with the umbrella. Reviewers do not have the ability to grant final approval or denial of a budget (unless they are also listed as an budget administrator).
Click here to read more about setting up budget reviewers and defining their rules.