Varchar is a short form for Variable Character Field. These characters stand for data, which length cannot be determined. In the real sense of it, Varchar is a type of data column that is found in DMS -Database Management Systems. The Varchar field can contain up to 4000 characters at maximum in Oracle 9i. The data limit for the row of MySQL is up to 65,535; while the field limit for Microsoft SQL Server 2005 is 8000.
On the other hand, Nvarchar happens to be a column that can store Unicode data at any length. 8-bit coding is the code page that Nvarchar should adhere to. A significant difference between Varchar and Nvarchar is their sizes, of which the former has a maximum capacity of 8000, while the latter has a maximum size of 4000.
This simply means that Varchar's single column can contain up to 8000 characters, while Nvarchar's single column can contain up to 4000 characters at most.