WS Retail is now a separate entity not run by Flipkart anymore. It was sold last year.
This was mainly to bypass the FDI laws. So WS Retail is like a wholesaler.
So WS Retail is a seller technically. Also you cannot say they run on different models, Flipkart does have more than a one seller so the model is still the same as amazon. Flipkart just eats other sellers at times with the WS Retailer's discounts and stuff. Just like amazon?
If every legal aspect is off the table then Flipkart is running WS Retail and other sellers are at mercy of Flipkart's(WS Retail) listing price.
Also Amazon.in sellers are all Indian (brick and mortar stores)sellers, so theres that.