Sack and Fire

Sack

To sack someone means to force them to leave their job or position. Usually, a person is sacked because of poor performance on a job.
The store manager was angry at Josh for leaving work early for three days in a row. He decided to sack Josh for his laziness and hire someone else for the position.
Being sacked from a job is much worse than being laid off. When you are made redundant, other employers will want to know the reason, and it could keep you from being hired somewhere else.

Fire

To fire someone means to let them go from their job. The word fired has a very negative tone and is usually used when an unpleasant event or action led to the person being fired. In the United Kingdom, sack would be more commonly used although British people are also very familiar with fire.
George wanted to fire his assistant, but every time he tried, she would cry. Finally, he sent her an email telling her to clean her desk and leave.
Last week, I was sacked from my job at the restaurant. The manager told me it was because I was too slow serving customers and that many people had complained about my work.
If many people are fired from a company at one time it is called cleaning house. Just like you would sweep out unwanted dust and dirt from your home, employers will clean house by firing the employees that are not performing well at their jobs.
Ana runs a small business in town. When her secretaries decided to take a whole week off for no reason, she cleaned house by sacking all three of them at once.
No small company can be successful when the employees fail to follow their boss's directions. If that happens, it is better to clean house than to keep these types of people on staff.