Contract of service
An agreement where one person agrees to employ another as an employee and the other agrees to serve his employer as an employee.
Employer is responsible for payment of wages,statutory deductions like PF,ESIC etc.
Employer has full control of employee-recruitment,dismissal,promotion etc
Employer has full control/ownership on factors of production.
Contract for service:
A contract for services,can be described as an agreement where a person is engaged as an independent contractor, like a self-employed person or vendor engaged for a fee to carry out an assignment or a project for the company. Under such a work arrangement, there is no employer-employee relationship.
many companies outsource conservancy services. The contractor concerned is on contract for a service-namely conservancy.
Contractor is responsible to pay his employees being deployed to compete main employers task.
Contract of service is often for long term,while contract for service may be for short duration or till a specifc job is completed.
I hope this helps.