No, Zac Efron is not a soprano.

He is more in the baritone range.

neither, he was a baritone

The usually accepted, from high to low, are - Female - Soprano / mezzo-soprano / contralto. Male - Tenor / baritone / bass-baritone / bass.

from top to bottom:

soprano

alto

counter tenor

tenor

counter baritone

baritone

bass

Alto and Soprano are voice parts, along with tenor, baritone and bass. Each part sing in a different pitch range; Soprano is the highest, then alto, tenor, baritone and bass. Tenor, baritone, and bass are traditionally sung by men, while the other two are sung by women.