Hey Seangheng,
Thanks for the question!
Person = Singular Countable Noun ( British English )
People = Plural Countable Noun (British English )
Persons ( used in Legal English in very formal situations ) ( British English )
People = The people of the world ( Generic Plural )
Peoples = The specific people in a part of the world ( Specific Plural )
The peoples of Cambodia
*usually peoples is usually used in Contrast mainly in Academic English
The peoples of Cambodia have different cultures from the peoples of Vietnam.
Person ( Singular Countable Noun ) ( US English )
People ( Not a word ) ( US English )
Persons ( Plural Countable Noun ) ( US English )
Hope that clears it up for you, the question is a good one and live on the radio I couldn't remember about 'peoples', but I have found out now.
Have fun with your studies,
Paul
