Employee Leasing vs. Temp
It is not uncommon in the business world to refer to employee leasing as temp services or to equate them. The two are, however, totally different, though they share many features.
In an employee leasing relationship, the employee leasing company becomes the employer of the record for the employees of the client company. The client company has already its employees when the employee leasing company becomes the employer of record.
In a temporary employment relationship, the temp agency finds, screens, and hires the temp who are placed at the client company.
Leasing employees is different from using temporary workers in that it generally refers to a situation where a third-party business "employs" your staff and you pay them a fee plus expenses to do it. In many cases the employee leasing company simply takes over clients existing staff of permanent employees, and there's little change in the actual makeup of the staff.
At the same time, it must be noted that in many cases, a temporary worker or leased worker will be considered an employee for purposes of employment laws and benefits requirements, so it may not make sense to lease employees in hopes of avoiding or circumventing these requirements. Usually, if a company controls the worker's work with some details, the company is considered the worker's employer. This is regardless of if the employee is leased or is a temp.