Regarding the editor, unreal is pretty amazing. 

...and that's a big IF. The editor ran like absolute rubbish originally on macs, to the point where it was actually unusable.

They've done a lot of work on that, but it's still miles away from the unity editor.

I think it's really hard to argue the unreal editor is better; it's a lot slower, but it does have some nice tools.

You also can't create extensions as easily (if at all?) as you can for unity.

As you say, they're two different things, and the unreal editor is actually not bad... but if you were to compare them, the unity one would certainly rank more highly.