The German defender joins the Bundesliga second-tier outfit on a permanent deal but the Croatia international forward is only going to the Red Bull Arena on loan
German defender Compper has moved to the Red Bull Arena as part of a permanent deal, having penned a three-year contract with Alex Zorniger's side.
Croatia international forward Rebic, though, has only switched to the Bundesliga's second tier on loan.
Compper only arrived at Fiorentina from Hoffenheim in January of last year but has decided to return to his homeland after being told that he was surplus to requirements at the Stadio Artemio Franchi by coach Vincenzo Montella.
Rebic, meanwhile, signed a five-year contract with the Viola 12 months ago but has decided to leave on loan in pursuit of regular game time.