Disinterested party, interested party
This is a distinction of role, not a criticism of agents. An appraiser is a disinterested third party with no financial interest in what the number turns out to be. An agent is a party to the transaction, which is exactly what makes a good agent effective at selling a house, and exactly why the two documents answer different questions.
A comparative market analysis is a pricing tool prepared by someone working toward a sale. An appraisal is an independent opinion of value developed under the Uniform Standards of Professional Appraisal Practice, which requires impartiality and requires the appraiser to say so in writing.
I do not prepare CMAs. I prepare pre-listing appraisals, which is a different product from a different position, and I would rather be clear about that than blur it.