They all look the same to me. Perhaps the devil is in the details, but visually, they all look like Windows, except the ones that look like MacOS.
The only system that doesn't look like either, that I can think of, is Plan 9.
Plan9 is certainly unique and opinionated. Nextstep/Openstep/WindowMaker and RiscOS are two others that come to mind.
Arguably BeOS/Haiku could count too. It’s less obvious later and with experience with Linux stacking WMs, but it was pretty obviously a different lineage at the time.