Induced draft and wind ventilation
The action of the draught fan makes the air inside the motor become thin, so the air enters the motor under the pressure of the atmosphere and ends up in the atmosphere.
The wind ventilation fan takes the air from the atmosphere, pushes it into the motor, and then internally into the atmosphere.
The comparison between the two approaches.
The advantage of Induced draft is that the air inside the motor is not heated by the loss of the fan itself. The disadvantage is that the internal pressure of the motor is lower than the atmospheric pressure.
The advantage of wind ventilation is that there is more pressure inside the motor than atmospheric pressure. The disadvantage is that the air entering the motor is heated due to the loss of the fan itself.