It's a grammatical difference.
As Aegis says, the word 'job' is countable. This means that:
* It has a plural form - jobs
* You use 'many' and 'few'
* You need to put 'a' or 'one' before it in the singular
The word 'work' is uncountable. This means that:
* It has no plural form
* You use 'much' and 'little'
* You can't put 'a' or 'one' before it.
He's looking for a job.
He's looking for work.
Are there many jobs here?
Is there much work here?
Sometimes nothing. Like in the sentences:
"Good job!"
"Good work!"
But you can't always swap them out because <em>job</em> is countable, and <em>work</em> isn't.
thank you both of you .i guess you're right
NB Your question should be 'What is the difference between work and job?'