GMV includes any fees or other deductions which a seller might calculate separately.
Site revenue comes from fees and is different from the monetary-value of items sold.
[1] GMV for e-commerce retail companies means the average sale price per item charged to the customer multiplied by the number of items sold.
In this case, the business model is based on a retail model, where the company basically purchases the items, maintains inventory (if need be) and finally, sells or delivers the items to customers.
It does not tell the net sales as GMV does not include costs involved and returns of products.