Which Photo do I Edit?

So I have a Nikon D5100 and when I upload photos, there are two copies of the photo. I understand that one is larger than the other so I edit/photoshop the larger one, but which one is the larger copy?

Having two of each means you are getting a jpg plus a RAW.

Is there any point to shooting in RAW? Opinions vary on this one - here is MY take on the subject:

• If you have to ASK about RAW, you're not ready for it and don't need it yet. However, you may wish you had RAWs in years to come, once you DO know about it.
• In most cases, it makes little real difference to our eyes, so why bother with the bigger file size if you don't want to.
• JPG is a lossy format, so if that is all you have, in time you can/will ruin the image (every time you open and save it, it deteriorates a little bit more). RAWs don't change.
• RAW is "as is", untouched, the real deal - JPG is the version that has been altered by the camera.
• Because RAWs have all the info there, you might find it is more likely that you can rescue underexposed areas.

Personally, here is how I like to operate:
• I always set my camera to both RAW and JPG, that way I have the choice. If I'm out taking snapshots just for the fun of it, I don't keep the RAWs afterwards.
• However, if I set up shop for a special project/portrait etc, I DO keep the RAW for future reference. I know it will be there, unchanged, and I can play with the processing again in the future.