Forum:Exiled force & Stardust Dragon

I have the question. Why The card "Exiled Force" can only tribute to activate it's effect in the controller's turn. While Stardust Dragon can tribute in any players's turn to activate its effect.

It this two card have the sentence "you can tribute this card"

My question is-- which turn that the tribution can do? why "exiled force" can do in it controller's turn but "stardust dragon" can tribute in both players' turn.