1) Instruction is the act or practice of instructing or teaching; education.
Explanation is the act or process of explaining.
Differences:
Instructions act as guidelines. They often appear as a series of steps or stages one must complete one after the other. Instructions are mainly associated with instruction or teaching.
Explanations are the act of explaining something. An explanation is a set of statements that describe a set of facts which aims to clarify the causes, context, and consequences of those facts. Explanations may establish rules or laws or they may clarify existing rules, laws or instructions.
2) Teaching is supplying a series of facts for the student to make of them what they will with guidance.
Educating is supplying the facts and then going with the students on the journey to uncover the knowledge that the facts supply.