There’s a direct counterpart to pop music in the classical song, more commonly called an “art song,” which does not focus on the development of melodic material.
(A)
But the pop song will rarely be sung and played exactly as written; the singer is apt to embellish that vocal line to give it a “styling,” just as the accompanist will fill out the piano part to make it more interesting and personal. The performers might change the original tempo and mood completely.
(B)
Both the pop song and the art song tend to follow tried-and-true structural patterns. And both will be published in the same way ― with a vocal line and a basic piano part written out underneath.
(C)
You won’t find such extremes of approach by the performers of songs by Franz Schubert or Richard Strauss. These will be performed note for note because both the vocal and piano parts have been painstakingly written down by the composer with an ear for how each relates to the other.
* embellish: 꾸미다 ** tried-and-true: 유효성이 증명된