The pictures displayed in your phone's Photo Editor application are the same as the ones in your gallery. They are not a copy of the pictures, they are the displays of the same files from the memory. If you would like to free some memory space, I advise you to delete the unwanted pictures from the gallery. Once deleted, these pictures will not be displayed in the gallery or in the Photo Editor app anymore.
Feel free to post any other questions you may have.
Photo editor is missing from my nokia 500...I used it quite often and one fine day its missing !!!! ...what do i do now ?? do i need to update my phone because it is still under warranty, or can i do something on my own ?? please suggest something