It can be for multiple reasons the scan suspend is usually if you have scan set to go over a certain ammount of hours and doesn't complete by then it will suspend. Or if there aren't enough resources available to complete the scan. Scan cancelled is usally either been stopped by user, SEPM administrator, or again not enough resources available. See similar thread in the link below.
https://www.symantec.com/connect/forums/scan-suspended-what-its-means