I'd say that a full-on track day is 10-times harder on a car than a drags or dyno. Dyno places NO load on brakes whatsoever, minimal tyre loads (relatively speaking), and the engine is taken to redline in 3rd or 4th once or twice. Drags you flog it for 10-20 seconds at a time, and brake once, then sit in a queue for 10 minutes). Track days you spend 90% of your time with either the throttle or the brake mashed to the floor, you put a lot of wear on the brake pads (usually after a couple of laps on street tyres and pads they're useless), you can go through half the tread on your tyres if you're not careful, you have loads on suspension components that never occur on dyno or drags. Clutch and gearbox get a serious workout as well. In short, dynos and drags are isolated performance tests, track days are the whole shebang. And it only takes one wall to ruin your day, and it's alongside the fastest point of the track too.