What is the difference between the Bandwidth and the Gain Bandwidth product that we usually find in datasheets of OP AMPS and comparators ? and why have we defined the Gain Bandwidth Product and we did not stick with the The Bandwidth parameter ?
Each is a variable Aol (open loop gain), BW tradeoff where the product is constant for the conditions given.
With an internal integration capacitor (aka compensation for all the transistor stages) around 10Hz the higher order effects are eliminated and now the closed loop gain is stable with negative feedback at unity gain (for most) where the bandwidth is maximum. GBWs can range from 10kHz to 300MHz for most but 10MHz is most common. That could be Aol=1e6 with 10MHz BW or Aol=1e7 , 1MHz BW as both have GBW of 10MHz/
This applies to Op Amps not Comparators which are not meant to be used with negative feedback for stable linear operation, but they are used with positive feedback to make hysteresis.