Because your career is where you spend a significant portion of your life, figuring out what you really want to do is one of the most important choices you will ever make. Confucius' advice was: “Choose a job you love, and you will never have to work a day in your life.” In this ideal scenario, you could take what you love to do, such as a favorite hobby, and turn it into what you do for a livelihood. For many, though, there is a significant difference between their hobbies and their careers.
Enjoyment vs. Ambition
The difference between your career and your hobby depends on the goal for each, whether it be ambition or enjoyment. A career is a profession or occupation that is specialized, focused and followed as your lifework. This requires a commitment to making progress and to excelling over time, which takes effort, practice and training. Hobbies, on the other hand, are defined as those activities you pursue for relaxation and pleasure. As such these are not considered a primary vocation. Those who have found the most fulfilling enjoyment in what they pursue for ambition have an enviable job.
Pleasure vs. Profit
While a career implies the job or business you pursue for your survival, you can also use hobbies to make money. Hobbies such as creative writing, painting, sewing, and woodworking offer you the ability to turn a profit from what you create. The difference between the two, at least for the IRS, depends on how profitable your hobby happens to be. Generally, you have to turn a profit three out of five years in order to declare an activity as a business.
Pleasure vs. Passion
Maybe you learned how to play the guitar for your love of music and found that you had a talent to turn it into a career. Hobbyists by definition will play in their own leisure time for their own enjoyment. Career guitarists practice hours upon end to hone their talent into a marketable skill. They work with professionals and play for live audiences in an ongoing attempt to perfect their craft. It is no longer simply something they want to do; it is something they are driven to do because of a desire to excel -- quite in addition to a need to earn a living.
Play vs. Work
No offense to Confucius, but whenever you decide to turn your hobby into a career you introduce work into the equation. Turning a hobby into a career significantly ups the ante on your overall goals. Ultimately you define that which is work and that which is play by what you wish to gain out of either endeavor, as well as how much you wish to put into it. As writer David Bruce put it: "A man chopping wood for winter is working. A man chopping wood in a lumberjack contest is playing."