Occupational role stress and job stress are interchangeable terms. A person may be stressed in their occupation/role/job for several reasons. They may have a stressful role where responsibility places them under constant pressure. they may have a dangerous role such as in the emergency services or they could have an emotionally taxing role.
Another form of occupational stress is where the person is undervalued or undermined in their role. This is a form of bullying and is a product or poorly trained, weak managers with personality disorders.
There are very many references on this subject, perhaps a meta analysis such as this one might help:
Intolerance of ambiguity as a moderator of the occupational role stress—strain relationship: A meta-analysis. Michael R. Frone. Journal of Organizational Behavior Volume 11, Issue 4, pages 309–320, July 1990