DIFFERENCE « String Functions « SQL Server / T-SQL Tutorial

12.4.1.DIFFERENCE function returns a value between 0 and 4 that reflects how close a match there is between the two strings.
12.4.2.Using String Functions to Search for Phonetically Similar Data
12.4.3.DIFFERENCE() is a wrapper around two SOUNDEX().
12.4.4.SELECT DIFFERENCE ('Redmond', 'Renton')
12.4.5.Use SOUNDEX(au_lname) and DIFFERENCE
12.4.6.DIFFERENCE('Nite', 'Knight')
12.4.7.Use DIFFERENCE in where clause