Not all Galaxies are created equal...even if bought from the same place (especially if not an official retailer). Maybe your phone was purchased before the update and the other one after? The only way to know for sure if both devices are the same version is by checking each phone's CSC (which will also give you the 'region' to which it belongs to). You can do that by going into the dialer and press "*#1234#". The third line is the CSC. If these codes are different in both phones, then they didn't come out from the same factory and were not meant for the same region.
The KitKat update is being rolled out S L O W L Y into different regions, so it may be that the white phone's region already got the update and yours didn't (I know that happened with mine until last week, when it finally hit my phone).
- - - Updated - - -
Not all Galaxies are created equal...even if bought from the same place (especially if not an official retailer). Maybe your phone was purchased before the update and the other one after? The only way to know for sure if both devices are the same version is by checking each phone's CSC (which will also give you the 'region' to which it belongs to). You can do that by going into the dialer and press "*#1234#". The third line is the CSC. If these codes are different in both phones, then they didn't come out from the same factory and were not meant for the same region.
The KitKat update is being rolled out S L O W L Y into different regions, so it may be that the white phone's region already got the update and yours didn't (I know that happened with mine until last week, when it finally hit my phone).