Have you observe the stock price difference on NSE and BSE. Why there is a difference between them if both the exchanges have the same companies?
Well here is the answer, when you buy anything in the markets, suppose tomatoes, there are different sellers having different prices.
Case 1: Demand
It all happens because of supply and demand, if one seller is having more customers, his tomatoes price will be high because of high demand.
Similarly, if the other seller is having less number of customers, the price of the tomatoes will be low because of less demand.
Case 2: Supply
If one seller is having less quantity of tomatoes, then there would be an automatic increase in demand, which will result in higher prices.
If the other seller has more supply of tomatoes then there will be automatically less demand, it will result in getting lower prices.
The demand and supply are calculated by the number of products and number of customers.
Suppose if there is a very large volume of buying customers, then even the large supply of products will not hold the prices to go higher.
In the same way, if there is very less volume of customers, then smaller quantity of products will not hold the prices to go lower.
National Stock Exchange (NSE) has very higher volumes of buying and selling as compared to Bombay Stock Exchange (BSE). There the prices of the stocks are generally higher in NSE than BSE.