First Response Time - Different Between Desk Report and Analytics Report

First Response Time - Different Between Desk Report and Analytics Report

I need some help to understand how these two reports are different.

In Desk, I go to Reports>Overview and look at the First Response Time.  The number I get is 7 hours and 13 minutes,

When I go to Analytics, and create a report for Average First Reply Time, for the same Department, and the same time period, I get 3 hours and 15 minutes.

What is being calculated differently here?