Of course there are differences. The Iditarod racers have dogs and a sled, and run a dangerous (and cold) course of 1,100 miles across ice and snow in the Alaskan wilderness. Bad things happen. Dogs and humans run the risk of death.
Nanowrimos have keyboards and coffee and probably cats. If there are dogs involved they are more likely to be lying on the writers' feet than running across miles and miles of frozen tundra. Don't let this fool you - Nanowrimo is also a dangerous race. Your cat could spill coffee on your keyboard. You could trip over a dog on your way to replenish snacks and break a typing finger.
You could get 20,000 words into your story and find out it sucks.
It always starts out well, with fanfare and excitement.
Sledders pack up survival gear. On the day of the race they take off to the sound of a cheering crowd. Wrimos also lay in survival gear - snacks, paper, pens, chocolate, tea, coffee and other more stimulating beverages. They plot, they plan. And on November 1st they launch their new books to the cheering of online friends and possibly even reality based family members.
The beginning is exhilarating.
But it's now two weeks in, and many wrimos may be feeling alone in the middle of a vast and windy wasteland.
Writers, on the other hand, can abandon a book, curl up in front of a warm fire, and drown their failure in wine. This may be comfort for the body, but the soul is in peril.
It's important to finish the book. It doesn't have to be a race. If Nanowrimo doesn't work out for you this year, that doesn't mean the book (or you) is a loser. You can still keep on writing.
I realized by the end of the first week that I'm not going to complete my 50k this November. The plot is complicated, the book was already half written and requires edits along the way, and I don't have enough time.
I'm good with this. I still plan to make it to the finish line. It's just going to look a little more like this: