im not touching "which is harder on the car", but i will say this.

sure, in drifting there are no lap times, no slips, no ets.. but again, you improve on your last run by going faster and wider, by sticking to a good line and making a clean exit.

people can tell the difference between a good slide and a better slide. you cant write it down on paper or pass it out on a time slip, but you can tell. it is subjective, but so are car shows, surfing competitions, and freestyle motorcross. there may not be strict criteria, but people know when theyre watching a skilled competitor.