Buddhas can take you to the boundary line of meditation and samadhi. That is the only difference between meditation and samadhi. If your mind has become utterly quiet and silent, but only the master is there, then it is meditation. If your mind has become so quiet that even the master has disappeared, it is samadhi. The last barrier is going to be the master. He will take you out of the world, but one day you will have to leave him too. And the real master will always keep you alert that you have to leave him one day, at the final stage.