Difference between all these Verizon date plans?

I'm not tech savvy at all. Now that I'm finally due for an upgrade, I'm going to get an iphone 4 cause it is free with a 2 year contract if I get it through the internet. Then they wanna know what data plan i want. 2gb, 5gb, 10gb, among other. What the heck is the difference between these?

The greater the number, the more data. 2 gb is a small amount, created for those who use lite usage… Checking and sending a few emails and minimal web browsing is an example. In contrast, 5 and 10 gb are for those who are moderate to "heavy ', which I really call moderate plus. They may stream video content, etc.