It can be seen that the piano has most of the energy sustained at the fundamental while the violin has energy distributed more evenly over many harmonics, hence the difference in sound.

We now understand timbre to have two broad characteristics that contribute to the perception of music: First, the distribution of energy across different harmonics not only serves as a recognition between instruments but also enables the recognition of a multifarious set of abstract tonal attributes (brightness, nasality, richness). Second, the temporal characteristics, especially the transient & note onset, or what musicians call the “nature of attack” is one of the primary perceptual vehicles for the identification, and location tracking over time of a sound source. This is important for bass & plucked string instruments such as guitars that contain little or no steady state sound at all . In this case, the shape of the amplitude envelope at the beginning of the sound will be key to the perceived pitch & tone quality.