Edge can do 4k netflix

With Edge, MS decided to re-implement some stuff through their own library. I don't have an exhaustive list, but one particular thing is that for a while, SubtleCrypto (used for various operations within JavaScript) was present, but some mandatory algorithms were not available in Edge while they worked fine everywhere else (and maybe even in the non-chromium based Edge, which I don't remember testing).

So, yes, there are differences beyond the integration of MS services. They are unlikely to matter to most people, but for dev it does reintroduce some weird quirks, as MS does.

Functionally they are the same. People that claim one is slower are just parroting what they've heard or experienced before

There are small annoying differences. The way it handles downloads is irritating. The settings menus are not well organized. There's a big stupid Bing button unless you remove it. It randomly fails to honor the option to open PDFs in an external program. It's nothing big, but if you're forced to use it for work, it's constantly annoying.