‘Psychotic disorders’ is an umbrella term for psychiatric conditions featuring psychosis, including mood disorders. Despite the prominence of psychotic symptoms across the psychotic spectrum, a distinction between schizophrenia and affective psychoses has been historically established. Findings from genetic studies support the aetiological overlap between affective and non-affective psychosis, although poor characterisation of the schizoaffective population still poses a challenge. Likewise, literature points to shared environmental risk factors between bipolar disorder and schizophrenia. Neuroimaging evidence suggest significant similarities in the pathophysiology of the brain between affective and non-affective psychosis. An overlap is also observed in other biological and behavioural illness markers, as well as in the pharmacotherapy of psychotic disorders. Current diagnostic entities may not accurately delineate the aetiology and pathophysiology of these conditions. Modern classification approaches, such as the RDoC framework, propose the adoption of aetiological factors and pathophysiological evidence to characterise patients, rather than categorical diagnoses based on symptoms.