Windows 8 has been engineered with a full set of gestures that work
system wide: swipe from the right to access the Charms menu, swipe from
the left to switch between running programs, swipe from the top or
bottom for access to the App bar in Metro apps.
In addition, it supports a full range of multi-touch gestures for scrolling, panning, rotating, and so on.
By contrast, Windows 7 has a limited set of touch gestures, and touch
support is essentially a replacement for mouse actions. In addition, the
quality of the touch experience is greatly dependent on third-party
hardware and drivers, which are of variable quality.
Touch targets in Windows 8 are optimized for the lower precision of a
finger (roughly 16 pixels) compared to a mouse pointer, which can point
to a single pixel. This optimization extends to desktop features like
Windows Explorer, which has been redesigned so that it works very well
with touch. If you try Windows Explorer on a touch-capable device in
Windows 7 and Windows 8, you can literally feel the difference.
The system requirements for Windows 8 specify that a compatible device
must support a minimum of five simultaneous touch points. Some Windows 7
devices support only a single touch point, making gestures like
two-finger scroll and rotate impossible.