By 'Nifty', people generally refer to the broad stock market index (Nifty 50). It is an index comprising of stocks from all sectors. There are 2-3 stocks of each sector having the highest market capitalisation. Bank Nifty, on the other hand, is a sectoral market index having only bank stocks. Nifty 50 is for tracking the overall share market and the economy as a whole, whereas Bank Nifty solely tracks the performance of the banking sector.