"Vocal range" is a term in singing that refers to the spectrum of notes the singer is able to produce, from lowest to highest. The "voice type" of a particular singer is a term used to describe the specific characteristics of a singer's voice, such as her timbre, tone and the transition points in her register. So while several people may have a vocal range of a mezzo soprano, these people will likely differ in the specific characteristics of their vocal type.
Vocal range describes the extremes of pitch that a singer can vocally utter, from the lowest murmur to the highest possible squeak. The three main categories of female vocal range, from lowest to highest, are contralto, mezzo soprano and soprano. For men, the three main vocal ranges, from lowest to highest, are bass, baritone and tenor. Contraltos and tenors are female and male singers who have very similar vocal ranges.
The range of a mezzo soprano encompasses the notes between the contralo's range and the soprano. This vocal range begins at the lowest point in the A note below middle C, and ranges to the F note two octaves above middle C. The tone of a mezzo soprano's voice also carries more weight, meaning it has a "heavier" sound, and is often less "bright" in comparison to a soprano singer. The total range of a mezzo soprano is approximately two octaves.
While a mezzo soprano's most comfortable singing range lies in the middle of the contralto and soprano ranges, a trained singer can potentially have a much larger range that encompasses either the contralto or soprano octaves or both. Trained singers can potentially coax more range out of their voices through practice and exercise in techniques.