And the 285H is lower performance than a 275HX.
Their laptop naming scheme at least is fairly straightforward once you figure it out.
U = Low-TDP, for thin & light devices
H = For higher-performance laptops, e.g. Dell XPS or midrange gaming laptops
HX = Basically the desktop parts stuffed into a laptop form factor, best perf but atrocious power usage even at idle. Only for gaming laptops that aren't meant to be used away from a desk.
And within each series, bigger number is better (or at least not worse - 275HX and 285HX are practically identical).
Don't forget the V series in there. I have an Intel(R) Core(TM) Ultra 7 258V in my Thinkpad. I think they're still being made. I bought an open box Thinkpad T14s Gen 6 with it - they come with a nicer GPU than the Ultra 7 255U.