What is the difference between supervision and instruction?

Supervision is to watch over someone. Instruction is to teach.

Ex. A teacher instructs a student. A parent may supervise the child while they do homework. The parent is to make sure the child works at the task. The teacher/instructor was to make certain the child knew how to perform the task. Often, these two roles are blended. A supervisor may see the need to teach/instruct a student or subordinate to perform the task in a better way.