It's a big branding issue as well.

I know Apple makes two laptops: MBAs and MBPs.

I don't know what all laptops Dell or Lenovo make. I don't know if they have ultrabooks, and if they do, what are their names.

When I buy a new Windows laptop, I sort by specs, not brand. I avoid a few brands (HP, Acer), but as long as I get good enough specs at a good enough price, I'll buy anything.

I don't care about specific models/brands in Dell, Samsung or Lenovo because I don't even know if they exist, and if they do, why I should give a crap about them.