Agree with @Buscar. You need to specify how you backed up and and how you got them back.
From question I guess that they were using iPhoto or Aperture to manage your pictures. I would guess that you dragged just the directories containing the pictures from the the backup drive back into the Application. If you to this you are actually loosing all your organization as you are reimporting them. You will have originals mixed with previews and edits all in one.
To Resolve. Find the backup of the complete package. It will be something like iPhoto Library or Aperture Library. If you open those with the respective application you should have everything as at the time that you backed it up.