Composition is the part of melody, that is, the "lyrics" part.

The arrangement is based on the entire song, and then adds other instruments and sounds (drums, guitar, violin, vocals and singing, etc.).

With composition comes arrangement, and arrangement can be organized by the composer.

Related information

Originally there was no concept of arrangement in classical music, because all composers wrote their own scores and stipulated the coordination of all instruments.

However, with the passage of time, people discovered more ways to express the music score in performances and daily practice. At this time, arrangement appeared, which did not affect the main melody and the original music. The content has further expanded the expression of the music.

In modern music, especially pop music, composition and arrangement are often two people, because many composers only have the grasp and inspiration of the melody, while the arranger has a better idea of ??how to embody the melody. Lots of skills.

To put it simply, the composer gives the skeleton, while the arranger gives the flesh and blood.