The tax appraisal is only meaningful in regard to the taxes assessed on your property. So low is better and people fight hard to get lower tax appraisals. If you want to see how meaningful the tax appraisal is, try selling it to the government for the value they appraised it at... never happen.
The CMA (competitive market analysis) is a much better yardstick of value, since it benchmarks your property versus the sales price of competitive properties sold in the recent past in your neighborhood. At the end of the day, a property is only worth what a willing buyer will pay for it.
Thank you @Mark Bosworth that’s how I understood their significance. Thanks for helping to clarify.