Final answer:
An 'on drive' is played when the ball is bowled towards the leg side, while a cover drive is played when the ball is pitched in line with the off stump in cricket.
Step-by-step explanation:
a) In cricket, an 'on drive' is played when the ball is bowled towards the leg side of the batsman. It is a shot played by moving the bat forward and swinging it towards the on side of the field. This shot is typically played against a delivery that is pitched on or around the leg stump.
b) A cover drive in cricket is played when the ball is pitched in line with the off stump. It is a shot played by moving the bat forward and swinging it towards the off side of the field. This shot is typically played against a delivery that is pitched outside the off stump.