Google Sheet Calculate Time Gap

I've tried to find a formula to determine the variance between two averaged time stamps (mm: ss) in the +/- format (for example -00: 35 or 01:35), but every time I've tried to do this calculation, I left a long decimal format (for example, 0.00000002262912423)

In my case, time is calculated by taking the total time on a website in seconds and dividing it by the number of visitors to the site.

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

1722730/11926 = 144.4516183

Then I convert it to the format (mm: ss):

144.4516183 / 60/60/24 = 02:24

What I'm trying to achieve is:

Time 1 | Time 2 | Variance

02:24 | 02:20 | 0:04

or

Time 1 | Time 2 | Variance

02:24 | 03:24 | -01h00

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