Final answer:
Hypochondriasis is the condition characterized by excessive fear of having a serious illness, without the presence of hallucinations or delusions, differentiating it from schizophrenia.
Step-by-step explanation:
The mental health condition that involves persistent fear and belief of having a serious illness, which leads to excessive health-related behaviors and anxiety but does not typically involve hallucinations or delusions, is Hypochondriasis (now often referred to as Illness Anxiety Disorder in DSM-5). On the other hand, Schizophrenia is a serious mental health condition characterized by symptoms such as hallucinations, delusions, and difficulty distinguishing between reality and imagination. Schizophrenia can also feature emotional abnormalities and social withdrawal. While schizophrenia includes psychotic symptoms like hallucinations and delusions, hypochondriasis does not.