I think the Inspiron are more for Home Use, so they may have better speakers, graphics card etc but trade off somewhere else. The Inspirons are more solid and I believe most have a larger CPU capability.
Large? Well it isn't small for the Widescreen Monitor alone. It's not the right machine if you are a Road Warrior put if you travel occasionally and want a desktop replacement I would recommend it. And for 150 or so you can get a Docking station that will put the Monitor piece much higher and comes with wireless kb and mouse.