What's the difference with using independent contractors and employees?

I'll just copy/paste from the IRS website:

It is critical that you, the employer, correctly determine whether the individuals providing services are employees or independent contractors. Generally, you must withhold income taxes, withhold and pay Social Security and Medicare taxes, and pay unemployment tax on wages paid to an employee. You do not generally have to withhold or pay any taxes on payments to independent contractors.

HOW TO TELL THE DIFFERENCE:

Facts that provide evidence of the degree of control and independence fall into three categories:

Behavioral: Does the company control or have the right to control what the worker does and how the worker does his or her job?

Financial: Are the business aspects of the worker’s job controlled by the payer? (these include things like how worker is paid, whether expenses are reimbursed, who provides tools/supplies, etc.)

Type of Relationship: Are there written contracts or employee type benefits (i.e. pension plan, insurance, vacation pay, etc.)? Will the relationship continue and is the work performed a key aspect of the business?