Preservation (umbrella term)
Maintenance of the architectural artifact as when it was received by the curatorial agency.

Restoration
Returning an artifact (architectural) to the physical condition that it would have been at a previous stage of its morphology.

Conservation
Physical intervention into the actual fabric of the building to ensure its continued structural and aesthetic integrity.

Rehabilitation
To repair an existing building to good condition with minimal changes to the building fabric. Undertaken to encourage re-use.

Renovation
The process of repairing and changing an existing building for contemporary use so that it is functionally equal to a new building. Major changes are allowed.

Reconstitution
Saving a building by reconstructing it in a piece by piece reassembly either in-situ or at a new site.

Reconstruction
The process of duplicating the original materials, form and appearance of a vanished building or structure at a particular historical moment, most often at the original site.