When someone is self employed or freelance employed he is working. When somebody is doing a permanent job and getting paid monthly for "work" he will have a job. In a job also he is doing work. But when we say work it does not necessarily mean a permanent job.
The terms 'work' and 'job' are certainly very similar, and some people would say they are one in the same. 'Work' has perhaps a broader meaning. It can encompass many areas of endeavour. For instance, you can 'work' at gardening, art, business, school or spiritual matters. 'Work' is perhaps more personal in meaning than 'job'. The latter implies that you are employed by someone else. 'Job' usually, but not always, implies that you are paid in some way. 'Job' is more formal, because when you are employed by someone else, there is usually some kind of contract or formal agreement in place. 'Job' is more specific in its objectives than 'work'. Employers usually give job descriptions; therefore, people who are doing a job often have a clear idea of the goals of the job. Despite these slight differences, 'job' and 'work' are very closely related and are often interchanged in language.
I'm a bit nervous. I'm starting a new ......next week?