Once you start to collect classical CDs , and get familiar with the most famous works of classical music, you will notice that there are so many different versions of the same work available, and may get more than one version of the same work. Or you may hear a performance on a classical radio station or at a live concert of a given work by a different orchestra and conductor, or instrumentalist from the CD you own.
This is where things really get interesting. You will notice that different conductors, violinists or cellists do the same work very differently. Just as Olivier and Gielgud were very different as Hamlet, different musicians will have different ideas on how to perform a given work. Two conductors will record a Beethoven symphony, and the versions may be vastly different.
The tempos, or basic rates of speed of a performance, may be quite different. One conductor may do a long symphony, and it might last up to ten minutes longer or shorter than a different version. A composer may mark a movement with the Italian word Adagio, meaning that the tempo is rather slow, but different versions will still not seem to be at exactly the same speed. If you get the famous recordings of the nine Beethoven symphonies by the legendary Arturo Toscanini (1867- 1957 ) on RCA BMG, you will notice that the performances are very driving and impulsive , even agressive sounding. Then listen to the equally famous performances by the great German Otto Klemperer. (1885- 1973. These recordings are considerably slower; the music sounds broad, deliberate and majestic. Which conductor is right ? The answer is that both approaches are valid, although different fans and critics will often tend to prefer one over another. Decide for yourself.
Other musicians will add nuances which may be lacking in other versions. Musicians often use what is called Rubato, an Italian term meaning "Robbed". That is, they may speed up or slow down in a subtle way in places where it is not marked in the music by the composer. Playing music in a rigid, metronomic fashion is not what most composers intend. They will specifically write Accelerando or Ritardando in the music at times, meaning in Italian, speed up or slow down gradually. But the tempo can be subtly varied. Sometimes musicians overdo and exaggerate the rubato, and if the composer hears the performance, he or she may be unhappy about this. Conductors such as Leopold Stokowski (1882-1977), and the great German Wilhelm Furtwangler (1886- 1954 ), tended to use much more rubato than Toscanini, who hated excessive use of it, and was sometimes accused of being too rigid and unbending.
Different conductors favor different kinds of sound from their orchestras; Stokowski was famous for a luxurious richness of sound, while Toscanini favored a lean, mean , trimmed down sound.
It would be awful if every musician played the same work exactly the same, but fortunately, that doesn't happen. Vive la Differance !