Final answer:
Nineteenth-century orchestral music differed from eighteenth-century orchestral music in terms of forms, genres, and orchestration. The music of the nineteenth century saw improvements in woodwind and brass instruments, leading to the addition of more winds in the orchestra. Composers also wrote music for public concerts and festivals with large audiences.
Step-by-step explanation:
In the eighteenth century, composers were primarily interested in forms, melodies, and harmonies that provided an easily-audible structure for the music. Classical composers focused on symphonies, concertos, sonatas, and operas, using strings and keyboard instruments with small groups of winds added for color.
On the other hand, in the nineteenth century, there were major improvements in the mechanical valves and keys of woodwind and brass instruments. This led to the addition of more winds to the orchestra, making their parts more difficult, interesting, and important. Improvements in the mechanics of the piano also made it the symbol of Romantic music.
The music of the nineteenth century was also influenced by the rise of the middle class, as composers were often writing for public concerts and festivals with large audiences. Additionally, composers in the post-Romantic era focused on producing strongly nationalistic music.