Dell UltraSharp 24" VS 25"?

Question

Monitors

Dell UltraSharp monitors have been repeatedly recommended on the toaster. At the moment I'm looking for a monitor that will primarily be used for work (web development), but sometimes for watching videos and playing games.
Do I understand correctly that the U24* line was replaced by the UP25* line or is the main difference in the aspect ratio 16:10 VS 16:9 and the resolution 1920x1200 VS 2560 x 1440?
24" Dell UltraSharp U2412M Black
24" Dell UltraSharp U2415 (210-AEVE)
25" Dell UltraSharp U2518D (210-AMRR)
25" Dell UltraSharp UP2516D Black
What are the benefits? Facilities?
PS Currently using 19" Samsung 913N
Thank you!

Answer 1

I use something similar to U2415 (but with a higher resolution, not fullHD for sure) at work, U2518D at home.
Specifically, I did not notice a strong difference in the picture. The U2518D has a slightly larger selection of modes + something like HDR, but I'm not sure if this is not marketing.
It makes no sense to take old monitors. Take the UP2516D - it's just fire - enough thin frame, good adjustment, excellent set of connectors. The U2415 does not like the touch buttons - it's very inconvenient.