Dear Himani,
These words are not synonymous as Job Satisfaction is a sub-set of Employee Satisfaction.
An employee can be well satisfied with his job but not overall satisfied due to various other reasons. The job that the employee is doing may be good for her/him and s/he likes the job but he may be dissatisfied bout something else in the organization like the process of performance appraisal, employee recognition, a bad boss, poor compensation package etc.
Regards.
byomjeet