A certified appraisal is a forma l, impartial estimate or opinion of value, usually, written, of an adequately described property, at a septic date.  It is prepared as a result of a retainer, for reliance by identified parties, and for which the appraisers accepts responsibility.  Only a state certified appraiser can provide a certified appraisal.A comparative market analysis of broker’s price opinion is an informal estimate of market value based on comparable sales in the neighborhood, performed by a real estate agent or broker.  You can do your own sum cost comparison by looking at recent sales of comparable properties in public records.  The records are available at local recorder’s or assessor’s officers, through private companies increasingly, through such sources as Domania or Yahoo etc.The most important difference between a certified appraiser and a broker or real estate agent is their motivation.  A broker’s typical goal is to obtain a listing and earn a commission.  Although most brokers and agents are honest, some might tell you what you think you want to hear.  A certified appraisers is independent and has not axe to grind.  They have no ulterior motives.  Their only concern is to deliver a fair, accurate, objective appraisal.