Count measures rows. Count distinct measures different values of a chosen field. When several breached Task SLA rows reference one incident, a distinct Task count measures affected incidents without counting that incident twice. Neither figure is wrong when its unit is stated correctly.
Mean time to resolve needs a defined population and consistent timestamps. This course calculates elapsed hours from Opened to Resolved for Resolved and Closed incidents with valid nonnegative intervals. Open records and invalid date pairs are excluded. It uses elapsed time, not business elapsed time. A resolution crossing midnight still has a duration based on both timestamps. Define these rules before comparing teams. Rounding a number for display should not replace the calculation or hide the population used.