I don't really think there's much of a difference I'm pretty sure that Kodansha just released the Japanese version of the manga,you would technically see the same pictures but instead of words you'd see Kanji/Kanna (Japanese characters in the word bubbles),Tokyopop is an american mangá publishing company,so you would see words instead of the Japanese Characters..so there's not really much of a difference,just what language it's written in,is the difference! hope I helped!:)
