rule = 制定了的规则
law = 确定了的规则
regulation = 规定了怎么做叫符合rule，怎么叫违反rule. 字面上regulate是“正常化”“规范化”的意思
principle = 某种概念，是rule的理念

e.g
based on the principle that "fried eggs are better than boiled eggs", there were rules among the community that you must fried the egg and not boil them, which was later officially made into law, and based on the law the overseeing department made regulations to define the correct procedure to cook the egg to make it considered "fried"