What Makes Grand Pianos Sound Better?

Grand pianos are seen as the pinnacle of all instruments, and are widely associated with the glamorous jazz scene, and classical recitals. But what is it exactly about the grand piano that makes it sound better than other types of piano, and is the fact that grand pianos are considerably more expensive really justifiable?
Grand pianos are a relatively modern technology in piano design. Furthermore, they have proven to be the preferable design of choice for most of the world's top pianists and enthusiasts. They differ from the other major classification of upright pianos in a number of ways, largely relating to configuration and size. The grand piano strings horizontally, and benefits from the force of gravity in its mechanism. Additionally, its sprawling structure allows for a fuller sound to resonate through the bridge, giving an impressive tonal distinction between grands and most upright models. Uprights on the other hand strive to be tight and compact, whilst also affording similar tonal quality. Of course, something has to give and with uprights, it’s the overall sound quality which is simply non-comparable to that of a grand. However, the compressed mechanism on the upright is beneficial as a small and compact instrument for practice and smaller public recitals.
Additionally, the grand piano also allows more accomplished pianists to perform ornamentation and certain other musical features thanks to a special lever, which holds the hammer above the string for longer. This means that by rapidly tapping the key, the hammer has less distance to move to reach the string which ultimately correlates to an increased ability to perform ornamentation and more complex staccato rhythms. With the upright design, it is impossible to include this feature, therefore you will never be able to achieve the same overall responsiveness and feel as with a grand piano, and the more accomplished player should feel limited by the scope for ornamentation on the upright.
The fact that the grand piano occupies more space allows its mechanism more freedom to strike the string clearly. Additionally, the horizontality allows for a deeper resonation through the wood which adds to sound. Throw in the added benefit of the repetition lever, and you've got yourself a quality, unbeatable sound. Although the uprights really can't compete, they certainly have the edge when it comes to space-efficiency and cost. It really is a case of determining your needs and objectives, before selecting the piano that's right for you.