Under the streamlined student visa processing arrangements, eligible student visa applicants from participating universities and eligible non-university higher education providers are assessed as though they are a lower immigration risk, irrespective of their country of origin.

If you are eligible for streamlined student visa processing you are not assigned an assessment level. This is because under the streamlined visa processing arrangements your student visa is assessed as though you are lower immigration risk.

If you are eligible for streamlined student visa processing you will generally have reduced evidentiary requirements when applying for a student visa.

Refer: http://www.immi.gov.au/Study/Pages/Streamlined-student-visa-processing.aspx