There just a computer program, voice synthesizers, looks like you've got some decent antwoorden but if u really want to know a lot about all the different Vocaloids try their wiki
link There are currently 34 different Vocaloids singing in Japanese, English, Korean, Spanish, and Chinese
Currently 4 meer vocaloids are in the making and they are updating many of the existing vocaloids voice banks. The most populair vocaloids are Miku, Rin+Len, Gumi, Gackupo, Kaito, Luka, and Meiko.
I gotta get out of the house more..... ^^" cause that was all door memory....