[solved] What makes this portion of the classic score sound so different form the original sound of the piece?
Here is a portion of the score of Tchaikovsky's "Dance of the Reed Pipes" from "Nutcracker" that I have downloaded from the public domain of musescore.com:
And here is the same piece (starting from the same point) on YouTube:
Please, listen to the first few measures of both sources. I have no reasons to believe that the score has any mistakes in it - it is done professionally and obviously the creator of the score knew perfectly well what he was doing. However, when I listen to that part when majority of instruments start playing (the fourth measure of the portion), not only do I sense some disbalance in volume levels, but even some wrong notes. If you listen to the same spot on the YouTube video, you don't hear anything of that and don't even get the feeling like really a lot of instruments start playing.
Why is it so? Can anyone here who is both a professional musician and a skilled Musescore user explain this to me, please?