The words principle and principal are pronounced in the same way but they do not have the same meaning。
这两个词principle和principal读音相似，但是这两个词的含义不同。
Principle is normally used as a noun meaning ‘a fundamental basis of a system of thought or belief’， as in：
Principle一般作名词用，表示“一种思想体系中的基本原理或原则”，比如：
This is one of the basic principles of democracy。
这是民主主义的基本原则之一。
Principal， on the other hand， is normally an adjective meaning ‘main or most important’， as in：
另一方面，Principal常被用作形容词，表示“主要的或最重要的”，比如：
one of the country’s principal cities
这个国家最重要的城市之一
Principal can also be a noun， where it is used to refer to the most senior or most important person in an organization or other group， such as ‘the deputy principal’。 It may also refer to a sum of money lent or invested， on which interest is paid， such as in ‘the principal on the loan’。
Principal同样可以用作名词，用来指组织或者团体中最高等或者最重要的人，比如“副校长”。Principal同样也可以用来指“一定量用来投资或借贷的钱（这部分钱需要支付利息）“，比如“贷款的本金”。
