Identity Column

► Column with identity property contains unique system generated value in the table.

► Column with identity property is similar to AutoNumber field in MS Access.

► You can set start and increment value while setting column property to identity.

► Column with identity property contains unique values within the table.

Uniqueidentifier, GUID

► The column with uniqueidentifier property contains globally unique data.

► SQL server uses uniqueidentifier property for merge replication.

► Same like Identity Column, SQL server supports uniqueidentifier column that also contains system generated value.

► A column or local variable of uniqueidentifier data type can be initialized using NEWID function.