You people who say that "Vocaloids sound like/is Auto-Tune," cleary don't know how much more complicated the program is. (Then again, I've seen the layout of Auto-Tune and it doesn't look user friendly either).
Here is the difference, if you must know:
Vocaloid uses samples of human voices to create the titular 'vocal androids'. Auto-Tune uses a phase vocoder to correct pitch in vocal and instrumental performances. Two very different programs with very different ways of working.
The only reason I can say how people seem to confuse the two is that the Vocaloids do sound like they've been processed through Auto-Tune. But (unfortunately), that's what they're are; androids.
They're not going to sound human in the fucking first place! (Although with heavy editing, this can be pulled off, but most of the time, it falls into Uncanny Valley territory).
Vocaloid and Auto-Tune are not the fucking same program.