Only rexx the scripting language in common.
What I'd like to know is how much MS copied Amiga for Windows 95.
Not really the Amiga alone, but Windows 95 was the first version of Windows where what you see in your folders is mirrored exactly with the organisation of files on your harddisk. Program Manager in Windows 3/2/1 was terrible and pretty screwed up. By doing this Micro$oft had done the bare minimum to keep DOS/Windows corporate users from the huge financial upheaval that would be a corporate change over to anything else. And at that point is where competition effectively ceased to exist (no doubt helped by M$ dirty tactics to lock out any other competing OS or even application).
OS/2 was also a pre-emptive multitasking system, these did exist before Tripos (and hence Kickstart/Workbench) but I think Amiga was the first desktop OS to combine such a feature with a GUI interface. Maybe UNIX but is Unix a desktop operating system in 1985? You could argue it is not. Certainly in 1985 you wouldn't be running Unix on a PC or Mac so I would argue it isn't. Whether IBM saw this as a key feature thanks to Amiga I don't know, however IBM did use Amigas for some specific multimedia tasks within its own house so they knew all too well about the Amiga I would say.
Only Apple or Atari could directly rip-off Kickstart/Workbench though given it is in 68000 assembler, and neither of them even bothered to try to replicate the superb multitasking on Amiga.
