And the difference i could arrive, is:
Job Work: Contract is given to job worker, whereby material is supplied by the person giving the contract. So, job worker, provides pure service on such material available.., that means he works on behalf of the manufacturer...
Works Contract: Here, the job worker himself is manufacturer, as he not just provides service but also brings the material on his own. So, he works on his own for providing service...
Still, as i said, what if the Job worker finds that material provided by manufacturer is not sufficient for provision of service at his personal level/capacity, he would request manufacturer to provide additional material or will bring material on his own? and what will be its impact?