“What a psycho.” This could be referring to your crazy, deceptive ex-boyfriend (who is in reality a sociopath), the cat lady next door who does some strange things (who really just has dementia), or someone who has actually been diagnosed with a form of psychosis. Many people also use the word to describe a serial killer who has committed some heinous crime.

Mental illness and personality disorders consist of an array of complex, hard-to-pin-down disorders that are often confused — but avoiding misdiagnosis is crucial in properly treating them. With all the “psycho” in psychosis, psychotic, and psychopathy, it’s often easy to get them all muddled. In reality, psychotic and psychopathic are two separate, distinct disorders — and labelling everyone who falls under these categories as a “psycho” is certainly a faux pas.

The root word, “psych” or “psycho” is actually derived from the Greek word for mind, soul, spirit, or sense of living, breathing being. It’s interesting, then, that now among English speakers, the word “psycho” has such a negative connotation. The Alfred Hitchcock movie, Psycho, certainly colored the word with the feeling that it implies someone we should be afraid of — someone who is out of control emotionally or mentally. Indeed, both psychopaths and psychotic people might pose danger at times, though at completely different levels.

Psychosis

Psychosis is a general umbrella term for a wide variety of disorders. Also referred to as psychotic disorders or psychoses, these disorders typically involve losing touch with reality, manifested by delusions and hallucinations. Delusional thinking often occurs in psychotic people; this consists of believing that people are out to harm you or are plotting against you. Hallucinations (which occur in schizophrenia, for example) are also a symptom of some form of psychosis, and they involve hearing or seeing things that aren’t there.

Schizophrenia — along with brief psychotic disorder, delusional disorder, and others — is considered a form of psychotic disorder. People with bipolar disorder, depression, or other mental illnesses can often show psychotic symptoms (in the DSM-5, bipolar disorder is actually listed as a bridge between psychotic disorders and depressive disorders). But as with many mental illnesses, psychosis can often be a fluid category and definition, with aspects of it manifested in people who are psychopathic, sociopathic, bipolar, or depressed.

But here’s the major differentiating point between psychosis and psychopathy: People with psychosis aren’t necessarily crazy or immoral serial killers. Psychotic individuals suffer from serious mental disorders that require proper care and treatment, and anti-psychotic medications as well as cognitive behavioral therapy can help mitigate these effects. Psychosis isn’t someone’s fault, and neither does it mean the person lacks a soul or empathy. Instead, it is a mental illness that shouldn’t be stigmatized, just like any other form of physical or mental illness.

“[T]here are a lot of inaccurate perceptions of psychotic people as immoral people,” Scott Barry Kaufman, scientific director of the Imagination Institute in the Positive Psychology Center at the University of Pennsylvania, writes on Psychology Today. “This is simply not true. While some bad people such as serial killers have psychotic episodes… the vast majority of psychotic individuals are not immoral. In fact, many people who are psychosis-prone contribute positively to society.”

Psychopathy

Psychopathy, meanwhile, is generally the term that encompasses people who commit crimes and have no empathy for other humans or animals. Psychopaths begin exhibiting these qualities at a very young age; they have destructive impulses, such as hurting animals or bullying other kids, and they show no remorse, empathy, or sensitivity.

“Psychopathic refers to someone without a conscience, who exists on a spectrum from your con man (self-involved, uses others for own benefit, not prone to violence) to the serial killer (predatory, gets aroused by hurting people physically causing suffering),” Dr. Paul Puri, a psychiatrist and blogger, writes. “Psychopaths are scary because they seemingly have no limits to what they might do, including hurting others, just for their own benefit or enjoyment.”

Psychopaths also are generally considered intelligent, manipulative, and charming — as well as having an inability to learn from mistakes or punishment.

In addition, there seems to be confusion between differentiating psychopathy with sociopathy. There is a difference between the two, however; sociopaths are considered products of their environment or upbringing, while psychopaths are believed to have genetic or biological causes behind their character. Both psychopathy and sociopathy are considered forms of antisocial personality disorder in the DSM-5.

While people with psychosis can generally be treated with proper medication and therapy, it’s difficult to say whether psychopaths can be treated. In fact, most doctors and psychiatrists believe that psychopathy is an untreatable condition, and the only way to stop many such people from harming others is to put them behind bars. But others believe that early intervention is key: When kids begin showing psychopathic signs at a young age, persistent intervention from parents and teachers can hopefully make a difference in the long run.