1. Material: The keys on a xylophone are made of wooden bars, while the keys on a piano are made of plastic or ivory.
2. Shape: The keys of a xylophone have a flat rectangular shape. In contrast, the keys on a piano have a raised, slightly curved shape to accommodate the fingers of the pianist.
3. Sound production: The keys of a xylophone produce sound when struck with mallets. On the other hand, the keys on a piano produce sound when pressed down to activate hammers that strike strings.