Four numbers, four definitions
Zillow's ZHVI estimates the typical value across the housing stock. Zillow separately reported a $1,206,700 median sale price for July. Redfin reported a $1,349,107 median over a three-month period ending in August. Realtor.com reported a September median listing price of $1,212,450 and median sold price of $1,280,000.
The arithmetic difference between Realtor.com's sold and listing medians is $67,550, or 5.57% of the listing median. That is a comparison of two market medians, not evidence that a typical seller received 5.57% above the asking price. Realtor.com's own sale-to-list ratio was 98%, which illustrates why unmatched medians cannot be treated as one transaction path.
Decision use
Use indices to understand broad direction, transaction medians to describe the mix of completed sales, and listing medians to understand current asking-price composition. Price a named property from a current, documented competitive set rather than selecting whichever public number is most favorable.