Utau and Vocaloid ARE different, people
well, this is the probably some cases where some people thought that they are the same because of their voice or some stories that they see on internet
UTAU is a freeware that was build with the same purpose as Vocaloid, but not as complete as Vocaloid, as you can see Utaus has more of an robotic voice than vocaloids
but, the plus point of using UTAU is you can make your own virtual idol, and you can even have the rights of your virtual idol, only thing you do is give her/him a voice!
so, it would seem that UTAU is a freeware to make a homemade virtual idol
and then, Vocaloids are software that was made in industrial scale and believe me, it is totally much different from UTAU
so, I suggest that someone should made Who's your favorite UTAUs thread here, so people will not be confused again