I knew Qubes created different partitions on the same hard drive.
I have an Alienware 15 r2 which has two drives. Using Legacy mode I have installed Qubes to the SSD, and Windows 10 to the spinning drive. (forgive me, I must have Windows for one or two uses) I do not recommend Alienware for use with any Linux. The XPS that can come with a Linux desktop, well, not as secure as using Heads.
All I can say is: If one only has one drive. “Windows does not play well with others.”