These words have associated meanings but should be applied carefully. Function means the kind of activity that is suitable and proper to a person or institution: "The function of this committee is to approve the budget." Work has many meanings of which the principal one is "toil," "labor," "exertion": "At what time did you finish work today?" Job refers to a post, location, or situation of employment; in fact, it is a colloquial and widely used synonym for position: "What job do you have in this firm?" Position refers to any type of work above the lowest kind of labor and applies to occupation that is desired: "He sought a position that would pay him more money." Work, position, and job are all overworked. Perhaps one of the following might express your meaning more exactly: station, place, rank, spot, task, project, responsibility, occupation. Job is slang when used to mean a theft or similar crime and a person: "She was a sweet job." "Lie down on the job" and "on the job" are trite expressions. As a verb, job is slang when used to mean "to cheat" or "to defraud": "He jobbed me on that deal."
Dictionary of problem words and expressions. Harry Shaw. 1975.