My undergraduate students become exposed, for the first time, to several aspects of literature which were taught to them in High School in a general way, unless they were A.P. students. They write papers for the first time that require a number of specific formats and literary evidence that can put them at a safe level of "apprentice".
Graduate students have already surpassed this level, and they are seasoned with essay-writing, finding evidence, and conducting more research. Students at this level are expected to be well-versed and communicative enough in the field to attain a level of "Proficient researchers". Once they earn their graduate degree they can go on and teach others,hence the term "Master". However, that is also changing, for Lit. majors everywhere are strongly adviced to pursue their PhD's in order to attain an expert level.