Same:

1.store unicode charactor.

2. A charactor is stroed with 2 bytes.

Different.

1. nchar  会自动填充数据到定义的固定长度；nvarchar 是数据有多长就存多少数据。

Example：

Create a table like below and store "A" in the two column.

CREATE TABLE [dbo].[AAAAA](

	[name] [nchar](10) NULL,

	[newName] [nvarchar](10) NULL

) ON [PRIMARY]

Result：the data length of the name is 20 bytes.

　　　　　the data length of the newname is 2 bytes.　　

You can get the data length with the below method.

select datalength(name) as Bytes, * from [dbo].[AAAAA]
select datalength(newName) as Bytes, * from [dbo].[AAAAA]