What Is The Difference Between Assessed Value and Market Value?

If both values are estimated at the same time by the same person, there would be very little difference.  Both values are someone's opinion based on other comparable sales information.

The Assessor compares your property to all other similar properties that sold in Falmouth during an 18 to 24 month period. A valuation model is created from the sales analysis. The values and guidelines derived from the valuation model are then applied in an equitable manner to all the properties that did not sell during this period.
For example, for the 2008 revaluation (when all properties were updated to current market conditions), properties sold between January 2006 through October 2007 were analyzed to create the valuation model.
 
A fee appraiser compares your property to three or four other similar properties that sold within six months or so. Adjustments are made to each comparable property to make it similar to your property. Then the most similar property is chosen as the best comparable to your property.