In TNG Ep. 1x20: Heart of Glory, Worf participates in a Klingon death ritual primarily involving a lot of screaming. They're announcing the arrival of a warrior in Sto'vo'kor. The body is then declared meaningless, an "empty husk".
In DS9 Ep. 5x2: The Ship, Worf joins O'Brien in a human equivalent of what he calls ak'voh, an entirely different death ritual. They're "guarding" the body until the spirit arrives in Sto'vo'kor. It's a much quieter affair.
In the first case, the body is very recently dead. In the second, it has been dead quite a while. If "announcement" takes place at the time of death, and then the body is immediately meaningless, there should be no need for a "guard".
Memory Alpha make a few suppositions about the disparity, and I have a few ideas of my own.
Has there ever been an official word addressing the disparity?