法則 and 規則: observed regularities and library rules
Compare a motion law confirmed by experiment and a word-order pattern with following a library rule and explaining a new rule.
法則 confirmed or noticed in a pattern
「実験を通して物体の動きの法則を確かめました。」 (The experiment confirmed a law governing the motion of objects.) 法則 (ほうそく) means law or rule. The experiment confirmed a law governing motion; the sentence does not describe enacting legislation or policy.
「単語の並びに一定の法則があることに気づきました。」 (I noticed a consistent rule in the arrangement of the words.) The speaker noticed a consistent rule in word arrangement. This example uses 法則 for a regularity in words as well as the motion law in the other sentence.
規則 followed and explained
「図書館では静かにするという規則を守る。」 (I follow the rule that everyone must be quiet in the library.) 規則 (きそく) means rule or regulation. The speaker follows the library's quietness rule, with a focus on compliance rather than an observed motion or arrangement pattern.
「新しい規則を全員に分かりやすく説明した。」 (I explained the new rule to everyone in clear terms.) The new rule was actually explained to everyone in clear terms. 全員に identifies the audience of the explanation, without establishing that everyone followed the rule.
Identify regularity and the object of compliance
The 法則 examples concern a regularity confirmed through experiment or noticed in word order. The 規則 examples concern a rule followed and a rule explained.
The English meaning rule overlaps between the words. Read the role in each sentence, preserving the distinction between explaining a new rule and everyone's actual compliance.
What do the motion 法則 and the library 規則 represent?
Show the answer and why
The first is a motion law confirmed by experiment, and the second is a rule followed in the library. 法則 also names a word-arrangement pattern; explaining a new 規則 does not establish everyone's compliance.