When a composer writes something for piano and he or someone else "transcribes" (translates in sound) the music for instruments other than for which it was written, the process is called "orchestration".   A lot of pieces started off for piano and "orchestrators" got their hands on it and re-wrote it for instruments.

George Gershwin the American composer wrote a terrific little piece "Lullaby" for piano (here it is) and then "orchestrated" it for string quartet. (here).  If you have a few minutes, listen to both versions...the original for piano is a whole lot different although it is EXACTLY the same notes.

There was a debate and a howl that went on when Turner Movies started colorizing the old black and white movies. Remember?  There has been a similar debate and furor in the music biz for a couple centuries now.
Just something that might be of interest.