Lenovo varieties

Everyone is always mentioning how the Lenovo S12 has two flavors: Intel Atom or VIA Nano. The Nano is cheaper. Why?
"The VIA has a slower clockspeed (1.3-GHz vs. the Atom’s 1.6-GHz) but in every other respect that matters it’s a more powerful chip: It’s got a faster bus (800-GHz vs. 533-Mhz) and twice the cache (1MB vs. 512KB). It’s also a 64-bit processor, although like most netbooks, the S12 I used ran the decidedly 32-bit Windows XP. (I don’t know if Lenovo intends to offer a version of the Nano-equipped S12 that runs a 64-bit version of Windows 7; it could be pretty darn cool.)" - Technologizer.
Then again, apparently the battery life is a little less - but that's what you get for more performance I guess.