For traditional brands of e-commerce, why is the product different between online and offline?

On my current experience, I summarize the following 3 points:

First: the problem of pricing; if the same models and materials online and offline, how to price online?

Second: the relationship between the traditional channel franchisees, distributors, regional agents of the interests of the problem, if the regional agents to take the goods and online the same models of the same material, the region's users to buy the online products, the damage to the interests of the regional agents;

Third: the customer groups are not the same, so the main products are not the same

So, in order to not damage the off-line Vested interests, the simplest and most economical approach is to develop a network channel of special products, online and offline to complement each other