1. Action:
- Harpsichord: The harpsichord has a plucking mechanism. When a key is pressed, a plectrum (or quill) plucks a string, producing sound.
- Grand Piano: The grand piano has a hammer action. When a key is pressed, a hammer strikes a string, causing it to vibrate and produce sound.
2. Sound:
- Harpsichord: The sound of the harpsichord is bright, clear, and percussive. Each note has a relatively short decay and sustain. The harpsichord's sound is often described as "jangly" or "tinkly."
- Grand Piano: The sound of the grand piano is rich, mellow, and resonant. Notes have a longer decay and sustain, allowing for more expressive and dynamic playing. The grand piano is known for its warm and versatile tone.
3. Dynamic Control:
- Harpsichord: The harpsichord has limited dynamic control. The volume and tone are mainly determined by the plucking mechanism and the construction of the instrument.
- Grand Piano: The grand piano offers a wide range of dynamic control, from soft (pianissimo) to loud (fortissimo) thanks to the gradual motion of the hammers and the use of pedals, such as the sustain pedal.
4. Timbre Variation:
- Harpsichord: The harpsichord has a single timbre determined by the characteristics of its strings and the plectrum.
- Grand Piano: The grand piano has a wide range of timbres and tonal colors due to the varying weight and hardness of the hammers, as well as the presence of multiple pedals that can alter the sound.
5. Pedals:
- Harpsichord: The harpsichord typically doesn't have pedals.
- Grand Piano: The grand piano has several pedals, including the sustain pedal (which prolongs the sound of all played notes), the soft pedal (which reduces the volume by shifting the hammers), and the sostenuto pedal (which sustains only the notes that are depressed when the pedal is pressed).
6. Popularity and Usage:
- Harpsichord: The harpsichord was widely popular during the Baroque era (17th and 18th centuries) and was used as a solo instrument, in chamber music, and as an accompaniment to vocal works.
- Grand Piano: The grand piano became prominent during the Classical and Romantic eras (late 18th to early 20th centuries) and is now widely regarded as the standard instrument for solo performances, concertos, and various musical genres.
In summary, the harpsichord's plucking action and limited dynamic control produce a bright, percussive sound. It was favored during the Baroque era. In contrast, the grand piano's hammer action and intricate mechanism provide rich, dynamic, and expressive tones, making it the predominant choice in contemporary music and classical music since the Romantic era.