What is the difference between class Attendance Rate and Avg Class Utilization?

Attendance Rate: The percentage of class enrollees who actually attended the class. For example, if 10 people sign up for the class and 9 attend, the attendance rate is 90%. A low attendance rate could indicate a class is desirable but members have difficulty making it to the class. 

Average Class Utilization: The percentage of available class slots that were filled. For example, if a class has 10 available slots and 5 people attended, the utilization was 50%. A class with low utilization could be unpopular or in a time slot that is not convenient.

Let's say a class has 10 available slots, 5 people sign up, and 5 people attend. That would be a 100% Attendance Rate, but only a 50% utilization rate.