(Also, the team itself have said in various ways that they'll never have as their goal to be a "Photoshop clone", as I understand it that's an unreachable and thus depressing goal. It's a lot more motivating to simply try to make something that works well than trying to cater to every whim of those who don't want to pay for Photoshop.)
They may look superficially similar, and at a high level have the same tools, but from a fundamental workflow point of view there are too many things that are just very different (non-destructive editing, smart objects etc).
the team itself have said in various ways that they'll never have as their goal to be a "Photoshop clone"
And that would be fine and if they'd done something unique or innovative with the UI and really made it their own. Unfortunately they didn't and they're stuck looking kind of like a half-baked Photoshop clone. And as long as that is kind of what they look like, then that is how they'll be judged.
From what I can tell the UI's look fairly similar too: https://gtchan1.files.wordpress.com/2012/06/5-gui-photoshop.... http://www.gimpchat.com/files/196_2012-05-12_214936.jpg There's various widgets that contain e.g. tools, layers, history, fonts, tool options; and of course each tool might have its own options.
(Also, the team itself have said in various ways that they'll never have as their goal to be a "Photoshop clone", as I understand it that's an unreachable and thus depressing goal. It's a lot more motivating to simply try to make something that works well than trying to cater to every whim of those who don't want to pay for Photoshop.)