'de facto' means 'of fact', and 'de jure' means 'of law'.
So, 'de jure' means what is official, whereas 'de facto' means what is reality. Sometimes these are antonyms in a given situation of course, if they are the same, there would be no need to use them. :)
'De facto' is far more common than 'de jure' though. I hardly ever see or hear the latter used.