People (specially guys that say they like track days more than autocross) confuse driving events with racing. They like to think they are racing. Yeah....
Autocross- The sport is different even if it shares some similarities. There is of course the element of car set up. But autocrossing is all about precision, driving the correct line, pushing the car to be at 10/10ths for the entire run. It is about being able to quickly memorize (not me!) or learn a course and getting it done in three runs. That is a skill in itself. Many people will eventually figure out the lines after 30 runs, but on your first run? When you have two dirty runs and now you absolutely have to get it done in one run? To be within inches of the cones at 60+mph and not make one mistake. Not one bobble. To finish that run out of breath. THAT is autocrossing. Relatively cheap, though you can also spend a ton of money. It is also cool that you get results and feedback with known good drivers to see how you are doing.
Time Trials of Solo1 events. Like autocrossing, just a little faster. Not as well subscribed and not many events. More safety requirements. More penalty for getting it wrong. I am going to guess most people have not done this (other than those that did the Lone Pine stuff).
Racing- Wheel to wheel is about being on the wrong line, because that other guy took away your line. It is about driving the same track over and over and driving it well near 10/10ths, but probably slightly less since you may not be on the optimum line. It is about having balls to take that inside line away, and be willing to trade paint to do it. It a step up in safety requirements and there are more risks. I would not wheel to wheel race the Noble.
But I have done it with karts. Can be very expensive. You also get results and feedback compared to other drivers.
Driving events. Often what is used as a point of comparison to autocrosss. More seat time, as in 2-3 20 minute sessions or more in one day. More penalty for messing up again. But with limited passing (depending on the organizers) you can drive your own line. Most people should not (and do not) attempt to drive 10/10ths in their street cars. You run on the same course over and over. There is no winner. But then there is no loser either. You just keep driving. You can drive 50 laps and mess up 49 of them and claim the one good one as your lap time. Yay! Good for learning car control, but then so it autocross. Can be a little more expensive each day. Results, depends if you keep track. Often you run against drivers that are not as good, so you can claim you are faster than a Ferarri... so there is that.
Each has its own merits. For me, wheel to wheel kicks ass... but I need a car to do it in and a large budget. I have neither. I like the idea of time trials, or time attack. Track days, I get bored.
Seriously, the course doesn't have to be all that long, half a mile of the right section of road could be awesome.