Antique Restoration is often done in
preparation for sale, or by a collector upon acquiring a new piece. The main
goal of restoration is to "restore" the original appearance or functionality
of a piece.
Restoration can be as simple as light cleaning to remove disfiguring dirt or grime, such as on the surface of a painting, or it may include near complete rebuilding or replacement, as might be the case with old automobiles or furniture.
There is a lot of difference between restoring and repairing. You may achieve functionality with a repair, but restoring an item properly is an art-form. Finishes may be stripped and redone, but it is essential that the original patination is retained, if possible.
While some of these practices are frowned on by many museums, scholars, and other experts (often expressed by the experts on Antique Road Show), for many people there is little value in an antique that is unusable or not able to be displayed.
On the other hand, an "over restored" item can actually take more away from its value than if nothing has been done to the item at all.
Therefore, restoration should always be left to professionals who are sensitive to all of the issues - insuring that a piece retains or increases its value after restoration.
Conservation, in contrast, typically aims to preserve the remaining material without necessarily being functional or looking new. There are several criteria for what work is necessary and how far to take any work performed.
Chiefly, is the object (book, painting, car, statue, etc.) actively deteriorating? Slowing or stopping deterioration and eliminating the root cause is the first task of the conservator. To this end, conservators, and antique Restoration professionals are usually trained in the science of materials and chemistry, as well as art history, archaeology, and other disciplines related to their areas of expertise.