Both Uses

symphony
in
Fahrenheit 451
(Edited)

With the brass nozzle in his fists, with this great python spitting its venomous kerosene upon the world, the blood pounded in his head, and his hands were the hands of some amazing conductor playing all the symphonies of blazing and burning to bring down the tatters and charcoal ruins of history.
p. 1.4 *

symphonies = music for orchestras
But with all my knowledge and skepticism, I have never been able to argue with a one-hundred-piece symphony orchestra, full color, three dimensions, and being in and part of those incredible parlors.
p. 80.8

symphony = classical music

Definitions:

(1) (symphony)
a long, complex piece of music for full orchestra (often in several movements); also, the orchestra or performance of such a work, or by extension any richly harmonious combination of many parts
(2) (meaning too rare to warrant focus)