One needs a license to do appraisals or sell real estate. The licensing requirements are different for each, and vary state to state. Most real estate agents are not licensed as appraisers.
Real estate agents do comparative market analysis (CMA) and present their findings to clients. A real estate agent helps clients understand the market by comparing the subject property (the one you are selling or perhaps interested in buying) to similar properties that have already sold, are currently on the market, or have contracts. A real estate agent will evaluate properties that went off the market without getting a contract, and recent trends in showings, inquiries, number of contracts, and overall market acitvity levels, etc. All of these factors are evaluated for the purpose of determining a market price strategy when offerng a property for sale or making an offer on an avaialble property. Market prices are determined by supply and demand. A Realtor looks all of the factors that indicate the recent and current facts to assist in purchase and sale decisions.
An appraiser uses closed sales for comparative purposes, and, under the right circumstances may employ other appraisal methods other than comparable properties. Most appraisals are done for financing reasons (refi or purchase), but these can also be done for other reasons.
What a Realtor is supposed to do depends upon what services they offer and what services you wish to hire. These are negotiable.
Determine what you want from a real estate agent. If you are not already in an agreement (buyer representation or listing agreement), meet and discuss your expectations with a few prospective agents and find the right match for you. You will find agents who will offer very limited services for lesser fees and full service agents who will do everything, explain everything, and be on-call 7 days a week from day one through closing and beyond. The choice is yours.
If you have already entered into a listing agreement, review the proposal you received for a review of the services and fees.
Best of luck!