Selling is a process of convincing a prospect on buying your product or service (it's a push strategy).
This could be done by the Salesperson at your door or your local shopkeeper or a luxury showroom salesperson or in the digital world, the e-commerce website nudging you to make a purchase.
A well marketed product as against a poorly marketed product requires less effort in selling.
For Instance, it is easier to sell ordering via Swiggy than it is to sell via FoodPanda. You are more likely to receive promotional offers or ads related to FoodPanda incentivizing you to try it.
In certain Industries where product and/or service differentiation is difficult to achieve, revenues are driven primarily by pushing products to consumers.
For Instance, In Telecom product differentiation between Airtel and Vodafone is minimal. These companies focus on selling and strengthening regions of operations.