I have been asked several times the difference between copyright and the right to copy.
When a client purchases his/her images on DVD they have the right to copy. Meaning they can print copies of the images or make a copy of the DVD.
Copyright means that the work belongs to the artist.
The exclusive legal right is given to the originator of the photo to print, make copies or publish the photography.
Clients do not have the permission to publish or sell the work to another party.
If the client is approached to publish an image for a sum of money, such as a wedding magazine, they cannot do so without the written consent of the photographer. Money and photo credit would then be given to the photographer.
I hope this blog post brings clarification to everyone.