Are visual hallucinations a schizophrenic symptom also, or only delusions?

Schizophrenic: Auditory, visual, somatic (tactile), smell, and gustatory (taste) hallucinations can all be present in schizophrenia -- but visual hallucinations can also come w/drug use & other organic pathology. You're right that delusions are important in schizophrenia: being persecuted; being referred to specially; being controlled; having one's mind read; thoughts put in or taken out of one's head, etc.

Visual: Agree. Can also be indicative of organic factors such as brain lesions or induced by substances such as medications or street drugs.

More complex: Visual hallucinations are common in many illnesses most notably delirium. But they can be found as a symptom in many illnesses. Delusions are common in some but not all forms of schizophrenia. Delusions can also be seen in a number of other illnesses. Delusions and hallucinations are symptoms not disease entities.