What are the differences between the screens?

The one marked just “Screen” comes as a “Part Only” or a “Fix Kit”. The “Part Only” includes (in addition to the screen) a pre-installed earpiece, bracket, front camera/flex cable assembly, and LCD backplate, which means the only thing you need to move over from your current screen is the home button. The “Fix Kit” includes all of that plus the tools you’d need to do the repair.

The one marked “LCD and Digitizer” is just the screen. You will need to move the earpiece, bracket, front camera/flex cable assembly and LCD backplate over from your current screen, in addition to your home button. It does not include any tools.

The easiest way is the “Screen” option but that might mean buying things you don’t need, and really it only removes about 5-10 minutes from the repair process if you’ve never done it before. If you already have the tools then you’re just paying for tools you don’t need. If your existing earpiece, flex cable, etc are good then you’re paying for parts that you don’t need.