Google sheet that calculates the variation between time

I've been trying to find a formula to determine the variance between two timestamps averaged (mm: ss) in +/- format (for example, -00: 35 or 01:35), but all the ways I've tried to do this calculation have left me with a long decimal format (for example, 0.00000002262912423)

The time in my case is a calculation taking the total amount of time on a website in seconds and dividing it by the number of visitors to the site.

Duration of the session (Total sec.) / Sessions = Avg. Duration of the session

1722730/11926 = 144.4516183

Then I convert it into format (mm: ss):

144.4516183 / 60/60/24 = 02:24

What I am trying to achieve is:

Time 1 | Time 2 | Difference

02:24 | 02:20 | 00:04

or

Time 1 | Time 2 | Difference

02:24 | 03:24 | -01: ​​00

Unfortunately, subtracting these values ​​as Time 1 – Time 2 will not give me the results I'm looking for.