Hobby is something you do in your spare time for pleasure and relaxation. People look forward to it because it's the time they can finally get away from their hectic schedules to do something they enjoy.
Passion on the other hand, is something you love and would gladly lose sleep over to do it. It is the fuel that keeps you awake 3 o'clock in the morning, the drive that keeps you going even when everyone else thinks you're crazy.
It is inspiring when you see someone strive for their passion. They quit their job, lose friends and money all for their love and belief. But it's devastating when you mistakenly believe your hobby is your passion.
Passion is something you are willing to give up the chance to earn more money in order to do it, while hobby is something you are spending money on to feel better.
So if you planning to quit your day job and focus on your passion, make sure it isn't actually your hobby. The good thing is, if it's really your passion, you'll figure out how to make a living out of it.