What caused people in Jerusalem to change so much from "Palm entrance" to crucifixion day?

Are the same people that received Jesus with flowers when he entered the city the ones that also condemned him for crucifixion a couple of days later? Every single preacher I've heard suggested they were the same, but other sources depict the judgement given in Pilate's courtyard as done in a rush with many men "planted" by the priests. After the judgement was given, none of Jesus' followers, no matter how many, could stand the Romans fulfilling their order. Are there any references that encourage any of these views or maybe some other perspective?