HI,
even i'm having difficult to find the type of scan. The higher the time taken we can asume it as scheduled scan or manual scan. Since you know the scheduled scan timing, it is easier to differentiate between scheduled scan and manual scan (based on time), however it is also diffiult, as client would have missed the scheduled scan and triggered at some other time.
The scan which hardly ends in couple of minutes scanning few thousands are scan intitiated when the new definition have been installed on client machine.
Pete!