High resolution files are better quality and allow you to make larger high quality prints. If you are using a point and shoot camera that most people use and you are satisfied with the prints you are getting from Kodak Gallery, I would just stay with the regular account.
If you are using a SLR camera (can change the lens on it) then the files generated are larger and may be bigger than the Kodak specifications on the a regular account.
If you are getting the high resolution files from your professional photographer, then it would be best to get the high resolution account if you want larger prints with a better quality.