Earlier quoted context omitted.
Slightly different. Gorillaz band members are usually voiced by one real artist (although this artist can change from album to album), whereas Hatsune Miku is one step removed - while there was a real voice actress providing the foundation for her voice, the actual lyrics sung don't pass through any human mouth. The persona of Hatsune Miku also seems to have evolved a little more organically: the style and personalit…
So do they record and then playback, or is it voiced fully by computers?
Also, as far as making artificial intelligences compose and perform, it might be interesting to hook up Hatsune Miku to a Markov chain generator[1], and feed it a bunch of j-pop as input. Would probably take some fine-tuning and modification to get it to give output that the synthesizer would understand (as it would be dealing with both words and notes), but it's not too far fetched.
[1] Which isn't an AI by any means, being more of way of generating text based on statistical correlations between words in the input body of data, but it comes up with some rather interesting things.