Is Royal Canin Feline Urinary SO 33 the same as Urinary SO?

Is Royal Canin cat food "Urinary SO 33" the same as "Urinary SO"? I can't find any solid information on what the difference between them might be, or if it's just a re-branding. Urinary SO 33 is still for sale in some places (note name on the package in the picture).