Mass Appraisal vs. Fee Appraisal
Appraisal is an attempt to estimate the value of a property. Mass appraisal, what the county does, is the appraisal of groups of properties as of a given date using standard procedures. Fee appraisal, what is often done by banks, is valuation of a particular property at a given time.
In other words, for mass appraisal, similar properties are valued similarly using generalized data and information, while a fee appraisal is specifically done for an individual property considering specific factors and based on a particular point in time.