All tui group airlines (bar corsair) are all being rebranded TUI with a small 'operated by Thomson/tuifly/jaf/arke' sticker at the front door. The Dutch are deemed more open to brand change so went first. The brits less so, so are last to change.
I'm not sure I like the new large TUI logo on the arke a/c its a bit big and just doesn't look right. Black tui on the Eng cowls seems a bit odd with no other black on the livery.