qualifier

Qualifier is an abbreviation of www.

As a noun qualifier

is one who qualifies for something, especially a contestant who qualifies for a stage in a competition.

As an abbreviation www is

when used as a high-level qualifier in a website address.

As nouns the difference between qualifier and subregional

is that qualifier is one who qualifies for something, especially a contestant who qualifies for a stage in a competition while subregional is (sports) a tournament, especially a qualifier, held below the regional level.

As an adjective subregional is

of or pertaining to a subregion.