The second one is a laptop chip, you maybe need to brush up on CPU naming. I actually meant to have a laptop chip for the first as well but I made an error. M3 Max is used in both desktop and laptops. Stop thinking of M series in terms of desktop or laptop, it's meant to be a multi purpose chip. Even with Intel and AMD you see chips and dies getting reused between desktops and laptops.
Although if we are comparing desktop only chips then AMD have Threadripper Pro and Apple has M3 Ultra. I am pretty sure I know who comes out on top (hint: it's the one with up to 96 cores)
Apple definitely does desktops as M Ultra is only available in desktops and is too hot for Apple Laptops. Although to be fair I could see one of the gaming laptop companies maybe finding a way to make it work.