@themidiman
You will want to use the List Roles endpoint.
GET /api/v1/accounts/:account_id/roles
I know it says the "account_id" request parameter is required, but I haven't included it before and it worked.
I usually include the "show_inherited" request parameter set equal to true to get any roles that may be defined in parent accounts, but you may not need this if you are only looking at what is defined at the specific account level.
When looking at the results, those that have a "base_role_type" of "AccountMembership" will be account roles. However, the other base role types indicate course roles (i.e. "StudentEnrollment", "TeacherEnrollment", "TaEnrollment", "ObserverEnrollment", "DesignerEnrollment"). There is also an "is_account_role" property that you can check.
I haven't found a way to exclude the account roles from the request results, but they can be filtered out if you only want to look at course roles.