Answer:
The difference between W-4 and a W-9 depends on your profession.
Step-by-step explanation:
If you are asked to fill out a W-9 instead of a W-4 when you first start a job, it means that you're a freelancer, self-employed, or do contract work for a company.
W-9 is a Request for Taxpayer Identification Number and Certification.
While a W-4 is a Employee's Withholding Allowance Certificate.
The kind of taxes you might have to pay don't withhold any of the required taxes, like federal taxes or Social Security taxes.
Someone using the W-9 is responsible for paying the taxes themselves.