规律:for example, newton's law is a 规律. anyway, people observes some phenomenon and summarize something. the things which are summarized are called 规律. another example, u get up at 7:00 and sleep at 22:00 everyday. this is ur 生活规律---living law.
the character 规 means something which is created by people to limit something, to create some rule. for example, 圆规---bow compass
the character 律 means something that we MUST observe. for example, 法律---law
规则:rule, such as 游戏规则
规定:it is almost the same with 规则. this word highlights that the rule cant be broken.
for example, 这是公司的规定,每个人都必须遵守。 we dont use 规则 here.
规章:a system of rule. for example, 这份100页的材料是公司的规章制度.
the character 章 means chapter.
规矩:implicit rules of a society. for example, parent tells child that people mustn't say anything while eating. this is a 规矩. if u dont do like this, we say: 你没规矩。
another phrase: 我们做事必须有规矩,不能没规矩。