this would be funny if it weren't so frustrating...a Dell flat panel saga

Hi! I thought I wanted to buy a Dell flat panel monitor. I was trying to decide between the 1504 and the 1504 FPa. I just need a monitor that doesn't take up space. (I don't play games, or anything like that.) I have now talked to four Dell reps. None could answer this question: what is the difference between these two monitors.

In fact, one rep said: there is no differece; Dell just likes to have monitors in many different price ranges.

I pointed out they're the same price, but anyway...

I read the specs, they read the specs to me (then pointed me to the specs again). I just can't figure it out. Here's an example of my level of understanding: I know what to use USB ports for on my tower, but how might I use them on my monitor? (Another question no tech could answer.) I'm thinking maybe one is a newer version of the other (again, no tech knew).

Can anyone tell me why I might choose on of these monitors over the other?

Any help is much appreciated! Thanks.