Burnout, as defined in occupational health literature, is a syndrome of three dimensions: emotional exhaustion, depersonalization (cynicism, detachment), and reduced sense of personal accomplishment. It is contextual — tied to a specific work or life situation. When the stressor is removed, burnout typically improves. It is not currently classified as a medical disorder in DSM-5, though the ICD-11 includes it as an occupational phenomenon.
Depression is not contextual in the same way. It can emerge from chronic stress — including burnout — but once established, it tends to persist independent of the stressor. A depressed person on vacation does not feel better because they've changed location. They feel the same emptiness, the same anhedonia, the same cognitive fog. That failure of context-change to relieve symptoms is clinically meaningful.
The overlap is real and complicates diagnosis: both conditions produce fatigue, concentration difficulties, irritability, and withdrawal. The distinguishing features of depression include anhedonia that permeates all domains (not just work), neurovegetative symptoms (sleep and appetite changes), feelings of worthlessness or guilt, and in severe cases, suicidal ideation. These features point toward a biological process that requires medical treatment.
A person can have both burnout and depression simultaneously. Burnout is a risk factor for developing clinical depression. The clinical approach should screen for both, treat depression medically when present, and address occupational factors as part of a comprehensive plan — not as the only intervention.