Dell Latitude E6510 vs E6510 N series - What's the difference?

Question

Okay guys, this is NOT a direct shopping question. I was wandering around because I need a new laptop. I've popped into this machine.

Anyway: What's the difference?
I found two models on a price list.

E6510 - N Series - Ci5 : This says "Latitude E6510 : N-Series Base"
and the other one:
Latitude E6510 - ... : This says "Latitude E6510 : Standard base"

Whats the deal? Different case? Features?

Answer 1

The n Series is a Dell product line that does not ship with a pre-installed version of Microsoft Windows. Apparently prohibited from shipping computers without an operating system by an existing licensing agreement with Microsoft, Dell instead ships these systems with either the open-source FreeDOS operating system or the Ubuntu Linux distribution.

http://en.wikipedia.org/wiki/Dell_n_Series