Speed Test confusion

Hello, I run Windows 10 Pro 1909. Recently I upgraded to Fibre and ran some speed-tests to confirm all was well; this is where the confusion came in.
Using the identical speed-test I found a difference of 10Mg between results depending on which Browser I accessed the speed-test from.
Personally I feel the actual speed is that of the higher level and I have no complaint. However the question arises; why when using TalkTalk's own speed-test it indicates less when using Firefox and the 'correct and higher' speed when using Edge with the tests run only minutes apart?
I tried 2 independent speed-tests and in one case I got the higher speed in both browsers and in the other case the test indicated the higher speed when using Edge.
As already stated I do believe and feel I am receiving the contracted speed and I am quite satisfied but why the difference?
Thanks.
Yorky.

Lots of things effect it one key is what server its using speedtest lets you choose which server in can vary dramaticley if you let it pick and it picks one miles away. Second is traffic if its peak times that can recude speed and of coarse your cpu network usage at the time of test

I use Speedtest by Ooka from the MS store. It is stand alone and does not use a Browser. I have ATT 1Gb fiber and always in the 950Mbs range both ways.

Jim

10Mg difference in results is really next to nothing. My speedtest.net result just now was 453Mbps download (and that's pretty slow for my connection really). So whatever you mean by 10Mg difference, on my connection that would be a 2% difference. That could be anything from how many computers are accessing the internet on my LAN, how many users on are my cable broadband connect in my neighborhood, or what the traffic is on the server that speedtest.net is connecting to.

With all the COVID-19 school at home and work from home...ummm...insert expletive here...going on, there really is a huge increase in internet traffic, and I see it in a noticeable decrease in my internet speed.