There is a slight difference in the meanings of the words used which may be leading to the confusion.
"Disconnecting" from a game means leaving the table before the game is over. This action incurs a karma penalty, and that penalty is stronger for tournaments.
"Conceding" a game is when one player in a 2-player game recognizes that they are in a losing position, and wishes to let the other person win rather than prolong the game. This is a normal occurrence, but has been disabled for tournament games. You still need to play the game to conclusion.
Both words are similar in meaning to "forfeit," but I don't recall forfeit actually being in the documentation.
