The XPS 15 is getting a redesign, and the XPS 17 is the biggest XPS ever.
Dell Reveals Redesigned XPS 15, New XPS 17 : Read more
Dell Reveals Redesigned XPS 15, New XPS 17 : Read more
Perhaps one of the biggest differences is with ports. The XPS 15 has two Thunderbolt 3 ports, USB Type-C, an SD card reader and a headphone jack. The XPS 17 has four Thunderbolt 3 ports, an SD card slot and a headphone jack, but doesn’t have regular USB Type-C.