The simplest way to explain career change is to say that it is a move out of the occupation group you are in now to a different group. It is not simply a different job in the same arena.
For many people, when they talk about a career change, what they're actually doing is simply changing their job. If someone moves from one insurance company to another insurance company they have changed their job. If they move from an insurance company to doing alternative medicine, or if they move out of teaching to writing, for example, they have changed career.
When you explain career change in this way, it becomes a more significant move than simply changing jobs. When somebody changes jobs, even if it's a promotion, they still have many of the basic skill sets in place.
A change in career might mean developing a whole new skill set. This is why people are concerned about having to start at the bottom again. Sometimes it's possible to cross map your skill sets in interesting and unusual ways.
Career change is becoming more frequent nowadays, with people changing career up to four or five times in their working lifetime. No longer are people leaving school and staying in a career for 40 or 50 years.
One of the major reasons for this is that people are more aware of themselves and put more attention on how they fit into the greater scheme of things. They want work to match who they are and they want the essence of themselves represented in what they do.