Just to add a little to what has already been said, in general, AS tends to be fairly stable over time. If you exhibit the characteristics, you tend to have them with you all the time (although you may learn strategies to help lessen their impact). The symptoms also tend to appear in childhood. Schizophrenia in contrast tends to show itself in "episodes". One can live normally for long periods of time (although there is some evidence that schizophreics often exhibit characteristics of personality disorders throughout their lives), then, often in times of stress, the symptoms with show themselves in what is known as a psychotic episode. Schizophrenia sometimes appears in childhood, but more often in adolescence or early adulthood or even later.

As to the symptoms themselves, AS tends to manifest itself as a difficulty with reading other peoples emotions, or understanding other peoples points of view, having a strong interest in a narrow area, sometimes seeming obsessional to another person, and some difficulties with language eg in understanding metaphors etc.

Schizophrenia is characterised by the onset of psychotic episodes in which the person often has hallucinations like voices speaking to them - often very negative voices, and delusions. It can also be accompanied by difficulties in forming coherent thoughts and expessing oneself coherently.

Thats a very quick summary off the top of my head, but I hope it is helpful.

Bagpuss