In educational sense, their meaning is quite similar. Both class and grade can mean the level of educational development in elementary, middle or secondary school, in other words, students at a given level. Their second meaning is note, that is, which is given to measure or determine the quality of the work or educational development of students. Grade also means the military, naval or civil service rank. Class occurs in the field of science, as well. For example, in Biology, it is a taxonomic category, in Statistics, it is an interval in a frequency distribution.
