In music a singer or vocalist is a type of musician who sings, i.e. uses the voice as an instrument to make music. A lead singer is one who sings the primary vocals of a song, as opposed to a backup singer who sings backup vocals to a song or harmonies to the lead singer.
A leadsinger (in barbershop music simply called a lead) is one who sings the primary vocals of a song, as opposed to a backup singer who sings backup vocal(s) to a song or harmonies to the leadsinger.
Singers may also be classified according to the style of music they sing, such as soul singers or carnatic vocalists.