"work" or "job"?
Not an easy difference to explain, but we should remember that work is both a noun and a verb, but job is only a noun.

Generally, I work to earn money and make an effort to complete a task that is NOT done for fun or relaxation.
Tim is working in a bar to get some money for his summer holiday.
This work (l'attività, non specificata) is ,in fact, a holiday job (posto di lavoro stagionale)
So job is usually more specific:
- What's your job?
- I'm a baker.
Contrast :
He's looking for work (any activity that can provide an income) / He's looking for a job (un posto di lavoro)
He's out of work / He hasn't got a job
Note we can also do "jobs" (pl - "lavoretti") as a pastime, or for relaxation
I will be busy this weekend - I have lots of jobs to do around the house
If you want to go to England to improve your English how about looking for a job this summer helping with the Olympics in London?
Check out the official site, upload your CV, and you could be working there this year!