So, are these really different cultures?

The definition of culture is; the arts and other manifestations of human intellectual achievement regarded collectively. By this definition we can say that both 21st century american film soundtrack and 18th century European orchestra are indeed from different cultures. Music in american films are subdirectly used for entertainment, but their main use is to bolster the viewing experience of a film by adding more immersiveness for the viewer. 18th century European orchestra however was used explicitly for entertaining an audience.