I have absolutely no knowledge of these things, I admit!

I know that WiFi is something you can access, say, at a cafe to be able to get on the Internet, but my laptop stays at home so I never do this (I have Internet browsing ability at work).

I have a prehistoric flip-phone, not so "smart" but it pretty much does what I need it to do without getting me distracted by other things. So while I've heard the "4G" phrase and similar bandied about, I don't pay much attention to it. (I do have wireless in the house, tho, for my laptop and Roku streaming video; I just don't give it much thought unless I need to restart it when I get bumped off for some reason.)

But now that Amazon has brought out 2 new Kindles, one with 4G, I'm wondering what they all mean and how they improve your interaction with the device (boy, now isn't THAT a P.R. term!). For one thing, what would be the factors in deciding to choose the 4G over the WiFi version (assuming you want more than a basic 'reader')?

What is it about the 4G Kindle that makes it cost $500? I mean, that's pretty much the starting point for an iPad, right? (Even tho I realize they're not comparable in terms of what they allow you to do, that's still the price point at which Apple starts to attract new customers.)

(Yes, I know I can go to Best Buy to see for myself, which I have done. I just want the lowdown on the technicals.)