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.
Highlight the day-to-day activities of the position. This will help candidates understand the work environment and the activities they will be exposed to on a daily basis. This level of detail will help the candidate determine if the role and company are a right fit, helping you attract the best candidates for your position.