Is there a noticeable difference between the Titanium on the Ultra and the aluminium on the other models? I'm guessing it's the colours on the Ultra that stand out more.
Both materials feel cool to the touch when initially held. I'd say the titanium is a bit more grippier which might be relevant if you like to use your phone without a case.
The colours are matched more on the back and frame for the S24/+ compared to the S24U.