Historic preservation often serves as an umbrella term for related subjects such as restoration, rehabilitation, and reconstruction. While the four are very similar, they are also very different. And, in actuality, they are not interchangeable terms. What’s the difference?
For an easy explanation read Telling Historic Preservation Time by Kay Weeks on the National Park Service (NPS) – Technical Preservation Series (TPS) Online Education. Weeks explains the difference between the four terms with an analogy to clocks and offers the following:
Preservation focuses on the maintenance and repair of existing historic materials and retention of a property’s form as it has evolved over time. (Protection and Stabilization have now been consolidated under this treatment.)
Rehabilitation acknowledges the need to alter or add to a historic property to meet continuing or changing uses while retaining the property’s historic character as it has evolved over time.
Restoration depicts a property at a particular period of time in its history, while removing evidence of other periods.
Reconstruction re-creates vanished or non-surviving portions of a property for interpretive purposes.
Weeks’ article goes further and briefly discusses problems, benefits, and examples with each of the four treatments. Overall, it is a good introduction to the Secretary of Interior Standards for the Treatment of Historic Properties.
Aside from this article the TPS Online Education section offers many useful guides including tutorials about historic preservation tax credits, identifying historic character, a discussion on rehabilitation, treatment guidelines and more. Theses sites are designed to be informative but useful to the average homeowner. You do not have to have a degree in preservation to understand them.
Preservation in Pink 
cool, thanks! Useful for the archaeologist too. I’ve only heard of the terms “reconstruction” and “restoration” for at least places/sites other than the US.