People often define themselves by the things they care about and enjoy doing. What exactly is the difference between a passion and a hobby? Usually, people both care about and enjoy their passions and their hobbies. The distinction between the two is subtle, but it can make a big difference in the way a person thinks about how he spends his time.
Merriam-Webster lists 10 definitions for "passion." The one that applies here is "an object of desire or deep interest." "Object" doesn't necessarily mean "thing;" instead, this is "object" in its grammatical sense, as in the object of a verb. Your passion is something that you care about intensely or that you find very interesting.
A passion, therefore, is something that you intensely want to do. A person thinks about his passion all the time. Many people hope to turn their passions into careers -- most artists, athletes, writers and community service professionals choose those jobs out of passion.
By contrast, Merriam-Webster defines a hobby as "a pursuit outside one's regular occupation engaged in especially for relaxation." In other words, a hobby is something you do specifically for fun. There are as many examples of hobbies as there are types of people. People may enjoy reading, playing sports, birdwatching, collecting stamps, riding motorcycles, painting, cooking or gardening. All of these things are hobbies, and this list is far from exhaustive.
So what is the difference between a passion and a hobby? First, a hobby can be casual, while a passion cannot. Someone may enjoy doing jigsaw puzzles in his spare time but not feel a particular need to do it every day. Jigsaw puzzles would be that person's hobby but not his passion.
Second, a hobbyist is always an amateur, no matter how skilled he is at his hobby. By definition, a hobby is for relaxation and not for income; if someone who enjoys baking becomes a baker, baking is no longer her hobby. A person's job cannot be her hobby, but it can be her passion.
People usually feel much more strongly about their passions than they do about their hobbies. Passions are consuming, while hobbies are not.
Think of passions and hobbies in terms of a Venn diagram with two overlapping circles. Usually, hobbies are casual, but not necessarily. The more intense someone is about his hobby, the more likely that hobby also is a passion. Hobbies that also are passions may turn into a career; at that point, it is no longer a hobby since those are usually done in one's spare time.
The definition of a hobby includes the note that hobbies are for relaxation. Passions tend not to be relaxing because people feel too strongly about them. This contradiction limits the overlap between the two ideas expressed in the Venn diagram.