Well from the info above they say all of em have the LED backlighting. And only one model (that's a prefab unit) has the 256 memory, and none of the premium models has that. Why? I have no idea.
Example on page:Long Battery Life
Capitalizing on a high-capacity battery, Intel® Core™ Duo processor, innovative Hybrid Graphic System and a white LED LCD backlight
, the SZ Notebook can blaze through your workload and your entertainment demands for hours. It's an ideal mobile counterpart when you're on the go. With a battery life of up to 5.5 hours (6 hours for premium models), the VAIO® SZ Notebook gives you more from everyMore Realistic Colors
Light-emitting diode (LED) backlight technology provides a brighter LCD display and a wider color reproduction range. White light is produced by three LEDs with emission wavelengths very close to the red, green and blue primary colors, resulting in more realistic red and green colors.
And that came off the general sz info page, not related to only the premium notebooks.
Originally Posted by Vcdechagn
I think the 160 on up are the premium models. Premium means Carbon fiber display case and LED backlight. AFAIK that's the only difference. All the video cards are the same 128mb w/ 128mb hypermemory (or whatever it's called...uses main memory to add to the card memory). This has been verified by someone who had an S4x series I believe. Sisoft Sandra reported 32mb of video memory on the S4x and 128mb on the SZ. I don't remember where that post was, either here or on notebookreview.....