I once asked a Dell rep tod me something that sounded like it made sense, and it is what I tell people who ask me. He said, the Latitude is their business class systems and the Inspiron is more for home users. Although they may be just about identical, the Latitude line designed to have a longer life cycle. For example the parts/specs are less likely to change *as much* and are basically you are more likely to get an identical replacement motherboard or other component in two years, if needed. Also they are not as "flashy" in design, if you can call it that. The Inspirons usually have the very latest components, however tomorrow, they may totally change what goes in them. They have a few more bells and whistles etc.
Latitudes are usually a tad bit more expensive, as they are designed for the business class and longer life cycle.
As far as physically, I am sure they are about identical in their basic design.
At the time, it sounded as good of an explanation as I had heard.
