Why does a piano not sound quite like a guitar even both play the same note?

A piano and a guitar produce different sounds for the same note due to their distinct methods of sound production and tonal qualities. A piano uses hammers to strike strings, resulting in a percussive attack and a complex set of overtones. In contrast, a guitar produces sound through plucking or strumming strings, which creates a different attack and resonance. Additionally, the body shape and materials of each instrument influence their unique timbres, contributing to the differences in sound.