In marketplace businesses, these are frequently used interchangeably. But GMV does not equal revenue!
GMV (gross merchandise volume) is the total sales dollar volume of merchandise transacting through the marketplace in a specific period. It’s the real top line, what the consumer side of the marketplace is spending. It is a useful measure of the size of the marketplace and can be useful as a “current run rate” measure based on annualizing the most recent month or quarter.
Revenue is the portion of GMV that the marketplace “takes”. Revenue consists of the various fees that the marketplace gets for providing its services; most typically these are transaction fees based on GMV successfully transacted on the marketplace, but can also include ad revenue, sponsorships, etc. These fees are usually a fraction of GMV.