Chrome vs. Firefox Document Complete vs. Fully Loaded

[UMichStudent]

I am doing some work comparing webpage load times between Chrome and Firefox on different devices. However, as I have done tests, I've noticed something weird going on with the "Document Complete" and "Fully Loaded" metrics. On Chrome, these two values are different - document complete is a lower time than fully loaded, as expected (example Result URL https://www.webpagetest.org/result/18011...37c6667e1/ ). However, on Firefox, these two values are, in my experience, always the same, which does not make sense (example Result URL https://www.webpagetest.org/result/18011...3d965a82e/ ). Is this a bug with Firefox, or is it supposed to work like this? I am confused as to why this is occurring.