Differences between Unicode characters and non-Unicode characters in SQL

Unicode characters are standard characters, such as English, numerals, and Chinese characters are not supported.

Non-Unicode is the inclusion of Chinese characters and some special characters

nvarchar supports kanji, but takes two bytes per character
For example, there is a field such as: [Name] [nvarchar] (50) We insert "xiaoming" This record, only two characters actually occupy 4 bytes. We insert "xiaoming" 8 English characters, which actually occupy 16 bytes. In the [Name] [nvarchar] (50) field we insert "xiaoming", which actually takes only 8 bytes

If it is Unicode, you can use varchar
nvarchar for non-Unicode

Differences between Unicode characters and non-Unicode characters in SQL