Difference between class and grade in Korean
수업·급
수업class
수업 means a class, lesson, or study period, usually at school. You use it when talking about having class, starting class, or what kind of class you take. It is a very common word in everyday school life.
급grade
급 means a grade or level. It is often used with a number, like 1급 or 2급, to show how high or low a class, test, or skill level is. In school and study situations, it helps people talk about course levels, exam levels, or certificates.
The difference
수업 means a lesson or class that you take. It is the activity itself, not the level number of the class.