The choice of locale can affect the collating order of
NCHAR and NVARCHAR character data types.
The NCHAR data type
The NCHAR data type stores character data in a fixed-length
field as a string of single-byte or multibyte letters, numbers, and
other characters that are supported by the code set of your database locale.
The NVARCHAR data type
The NVARCHAR data type stores character data in a variable-length
field. Data can be a string of single-byte or multibyte letters, digits,
and other characters that are supported by the code set of your database
locale.
Performance considerations
The NCHAR data type is like the CHAR data type, and NVARCHAR
is like the VARCHAR data type.