Salvadore,
Taste the juice and you will have your answer. I will guess that the juice has very little flavor and the puree has great flavor, especially if you used heirloom pumpkins like Fairytale.
I most recipes that call for pumpkin puree there are problems with excess liquid. That draining will help.
FYI, if you juice a fresh pumpkin, the puree has almost no flavor and the juice is flavorful. You can take the juice and reduce it for use in custards. There is nothing more surprising than a silken pumpkin creme brulee made with heavily reduced pumpkin juice.
Tim