See title. Both of these translate as "principle" and I'm struggling to see how they are different. Thanks in advance.
原则 is principle of personal conduct
做人要有(原则) = A man has to have (principle)
工作至上是我的(原则) = My (principle) is works always come first
原理 is principle of physics
利用槓桿(原理) = Using the (principle) of leverage
利用虹吸(原理) = Using the (principle) of siphon
"I know the 原理 of something" means I know the reason why something works
"I know someone's 原则" means I know what someone would or would not do base on his principle (personal believe and conviction)
The 原则 (principle) of insurance companies is "to try their hardest to avoid paying their customers" (that's what they do as an unwritten rule)
Very few words translate one-to-one between languages, and they are usually very basic like you/me/water or simply loanwords. European language speakers often get confused on this topic after learning some other European language (which essentially shares a huge set of the same semantic fields with minuscule variations).
What is bundled together as "principle" in English (or rather, all IE languages sharing this post-Latin loanword) is not a single idea.
原则 is "principle" as in "man has his principles" - basic rules of behaviour". By choice.
原理 is "principle" in the sense "doctrine, theoretic base etc". By nature.
I thought that could be a simple distinction.
原理: theory, principles/fundamentals in science;
- a cardinal principle: 根本的原理;
原则: principle, rules;
- agree in principle: 原则上同意
The key is that in English the word principle can be used to denote both scientific theories and rules to regulate ourselves. Well, in Chinese, we separate it into two words: 原理 and 原则.
Hope this could help.
Previous answers are quite complete. I want to provide some additional information on "原则".
原则 also has a meaning close to "generally" or "usually". Means that a rule applies to most of the cases, but, importantly, it can have some exceptions.
Example: Generally, we don't approve applications for change of major for first-year students.
This sentence means that "there can be some exceptions for first-year students".
In addition to what others have pointed out (that 原则 & 原理 both could refer to "principle" or "rule"), 原则 usually refers to concrete principles and guidelines, whereas 原理 refers to the more abstract, theoretical, and/or foundational principles. Newton's book, Philosophiæ Naturalis Principia Mathematica, for example, is "自然哲学的数学原理" in Chinese.