Dissociation disorder vs schizophrenia?

Very different! Schizophrenia is a chronic psychotic illness. Dissociative disorders is a very different type of escape from reality that rarely involves psychosis. Treatment is also very different.
Contrast. The 2 disorders are very different, although both someone dissociating and someone with schizophrenia may appear "far away" to a casual observer. One of the crucial differentiating points is reality testing. In dissociative disorders, reality testing is intact -- in schizophrenia it is not. Schizophrenia includes delusions, hallucinations, & disorganized thinking, speech, & behavior.