It could also be that one of them is being unrealistic. I tried Windows 10 on a 2.2 GHz single-core Turion laptop with 1 GB of RAM, which meets the Windows 10 minimum requirements. Sure, it ran. If I tried to do anything, it crawled along so slowly as to be functionally useless, but yes, it worked, if your definition of "worked" means it didn't bluescreen or lock up immediately.
And that's with a CPU more than twice as fast as what 10 requires, supposedly.
Meanwhile, I've run Ubuntu-based Linux (Mint Cinnamon) on a dual-core CPU not much above 2 GHz, and it runs quite nicely.
The only real issue I have with Ubuntu is GNOME, and before that, Unity. If I wanted a half-baked UI that tried to straddle the line between touch and traditional mouse/keyboard, I'd go for Windows 10.