Webster's Definitions:
-Timbre: "the quality of tone distinctive of a particular singing voice or musical instrument"
-Instrumentation: "the arrangement or composition of music for instruments esp. for a band or orchestra"
My Definition: The quality of a sound or tone.
Timbre, really, is just how a song or aspect or a song sounds. So-how a sound sounds. Instrumentation is really just how the different instruments sound and how a composer or musician takes advantage of that sound. Every instrument and person has their own unique timbre. Sometimes things can sound similar, yes, but it's always at least a little different. Timbre is kind of like your musical fingerprint - unique for everyone and everything.
There are a variety of words you can use to describe timbre. You've probably even heard and used a lot of them before. Some examples are raspy, smooth, sweet, pure, harsh, etc. You can use adjectives like these to describe somebody's voice or any other instrument as well.
Really that's all there is to say about timbre and instrumentation. It's just your musical fingerprint and how your voice or instrument or the song in general sounds. And that's really all that there is to know!
