It's very difficult to say what the actual differences are, but you can click on either the 001, 003, or 004 and look at the Product Details below. But I can't say whether there are significant differences in the scanner itself. The 003 and 004 have extra things included, but whether that is worth the extra money is hard to determine, and is up to you to decide. Good luck. In my case, all I needed to do was to scan black and white documents for tax purposes, and the 001 worked surprisingly well for that.