In his book, Furniture Care and Conservation, well respected furniture conservator, Robert McGiffin, describes the difference between furniture restoration and furniture conservation.
"Restoration can be defined as the practice of repairing or reconstructing an object to return it to its original condition and/or appearance. Conservation can be defined as the practice of protecting an object from injury, loss, or violation. One who practices restoration (a restorer) of old furniture may advocate removing from a venerable piece of furniture a finish that has deteriorated with age, while a person who practices conservation (a conservator) may advocate retaining the finish and trying to stabilize it to prevent further deterioration."
Though Mr. McGiffin advocates conservation in his book, he also recognizes a need for both restorers and conservators, as does Hander Woodworking which is why they offer their customers both disciplines with equal competence.