Different online platforms follow different business models. And some may work more for certain product categories, while some may be better for certain other product categories.
In India, generally consumers think of Flipkart or Amazon when they think of books. Myntra is associated with clothes and Snapdeal comes on top of their minds when they want discounted items. So when you decide to sell online, you should ideally consider these factors before deciding on the platforms to be present on.
Have a look at the infographic below; though not hard and fast rules, they could be used in guidelines or pointers in figuring out what could work better for you.