A job specification could be considered a more precise job description that details the exact educational degrees, experience, skills, and requirements for a role. In most cases, these terms are used interchangeably and nearly always describe the same document.
Typically, organizations use their human resources or personnel department to create job description templates. In some cases however, a departmental group, a manager, or another individual (usually the direct supervisor of a position) might be responsible for creating one. In any case, make sure the creator of the template is familiar with the company’s or organization’s needs.