Nothing, they just have different store names, or you could say they have the same brand names but expressed differently.
The Roman numeral XXI represents the number 21
As of May 2009, Forever 21 does have a Plus Size clothing line. You can view more information about this at http://latimesblogs.latimes.com/alltherage/2009/03/forever-21-to-l.html, or shop at a local Forever 21 store.
XXI = 21
George Martin
XXI is the Roman numeral for 21.
XXI is the same thing as 21.
Freak XXI was created in 1998.
Converxencia XXI was created in 2009.
Hespèrion XXI was created in 1974.
x = 10 i = 1 xxi = 21
The Roman numeral of XXI is equivalent to 21
X is 10 and I is 1. XXI is 21.