13" MBP display resolution question

Question - my current 15.4" 2007 MBP has a display resolution of 1440x900. Time for a new Mac, and I am considering the 13" Air, which also offers the same display resolution: 1440x900.

I'm trying to understand what difference I would see as a user. Obviously the physical screen size is smaller on the Air (15.4 --> 13"), but if the resolution is the same on both machines, 1440x900, what "rubber meets the road" effect do I see as a user? Do I still have the same screen real estate, the objects are just scaled smaller?

Any insight anybody can offer would be superb. And a picture is worth a thousand words, so if you could show anything graphically or via screenshots, that would be greatly appreciated too.

thanks!
Mark