To expand on this, the differences come down to taxation. There are taxes in the use called FICA that are half-paid for by the employer for W2 workers and not covered for 1099 employees. Also 1099 workers are able to deduct business-related expenses from their income ta.
The most important distinction is clients large and small will try to rip off 1099 workers. The state labor office will not help 1099 workers. They must hire lawyers sometimes to get payment.