Which document serves to distinguish one job from another?

The correct answer is a job description, as it provides a detailed outline of the responsibilities, duties, and expectations associated with a specific position. This document serves to clearly define the role, making it distinct from other jobs within an organization. A well-crafted job description helps both employers and potential employees understand the specific requirements and qualifications needed for the position, as well as the scope of work involved.

While job specifications and job analyses also play critical roles in the hiring process, they focus on different aspects. Job specifications detail the qualifications and skills required for a job but do not outline the job's specific responsibilities. Job analysis, on the other hand, involves a comprehensive examination of a job's duties and the context in which the job operates, contributing to the overall understanding of the role but not serving directly as a unique identifier for the role itself. Job postings contain elements from the job description but are primarily used to advertise the open position to potential candidates, rather than to define the job uniquely.