Inspiron will come with a lot of Begware installed.  Vostro is for business and can be ordered with no begware, mcafee, etc just base windows and no trialware/shareware/begware.

It's not just preloaded software that may be different.  While the specs may be similar there could be a difference combination of hardware used in the manufacture of the lines.  The casing may also be a different material as well.  There can be a lot of differences that aren't going to show up just on a list of technical specs.

The hardware is more alike than different.  Both lines are pitched toward price-conscious buyers who are willing to sacrifice things like very long battery life, light weight, etc. for a low price.

The original 14R used the older Core i CPUs.  The new one uses the newer Core i (called Sandy Bridge).

My experience is that there is very little hardware difference.

Inspiron 910 vs Vostro A90 for example.

the vostros have an antiglare screen, the inspiron is glossy

I do recall Vostro came in Black whereas the Inspiron came in white, pink, blue, green etc.