Contralto is a coordinate term of soprano.

As nouns the difference between contralto and soprano

is that contralto is (music) the lowest female voice or voice part, higher than tenor and lower than soprano the terms contralto and alto refer to a similar musical pitch, but among singers, the term contralto is reserved for female singers; the equivalent male form is counter-tenor originally the contratenor altus was a high countermelody sung against the tenor or main melody while soprano is musical part or section higher in pitch than alto and other sections.