There are some differences between job and work. For example, when we're talking about business, job is countable and work is uncountable. We can talk about jobs with a number, for example, 100,000 jobs were created last year. Usually when we talk about work, we can't use a number, but we can say a lot of work or not very much work.
A job can be a position, like software developer. The work is software development.
To do a good job is to do something well, and we usually use it to talk about a single project, for example, the team did a great job on that campaign.
Work can also mean the place where we work. We say "I go to work at 9am every day." Right now, I'm writing this post at work.