I cannot believe this is a question. Some of these companies should pull their heads out of their a**!
Looking at the way I manage thrust lever position vs. the way the auto throttle does; I would imagine that the answer is that the autothrot' tends to "chase" the commanded airspeed.
Where as I would set a specific N1 relating to the weight, etc. and generally let the a/c ride out slight fluctuations in airspeed. Thus listening to the approaching aircraft, one might note greater audible variations of thrust when a pilot is employing the auto throttle.
P.S. This may NOT be right and applys mainly to heavy cat' jets. Any company asking this type of question should probably be avoided.