The federal regulations governing research with human subjects categorizes research based on what activities occur during the research. There are three categories of review - Exempt, Expedited, and Board-reviewed. Exempt and Expedited research is then broken down further into additional categories.
"Non-Exempt research" is research that falls into either one of the Exepedited categories or Board-reviewed research. This is to distinguish it from Exempt research. Non-Exempt research has additional requirements such as a more detailed consent process that Exempt research does not.