The Nokia is thicker (and heavier) due to the sliding keyboard, the Nexus One looks a bit sexier.
They both sport a 800 x 480 (3.7") screen.
As far as software, they seem to be packaged with much the same stuff.
The OS is different between the two, but I don't think that it's enough of a difference to flip my mind one way or another.
The Nokia app store is available for browsing from any machine, but the Google app store seems to require a android handset to view all applications. (This bit really sucks!)
The Nokia has 32GB standard, the Nexus One only has 4GB.
I think that the Nokia also has a better lens system on the camera.
Is there some sort of 'deal buster' that I am unaware of with either phone? What say you all?