Explanation:

- Cardiologists specialize in diagnosing and treating heart and cardiovascular system disorders.

- Nephrologists focus on kidney health and diseases affecting the renal system.

- Pulmonologists are doctors who treat respiratory system conditions, such as lung diseases.

- Psychiatrists specialize in mental health, dealing with emotional, behavioral, and mental disorders.

- The first three professions specialize in physical organ systems (heart, kidneys, lungs).

- Psychiatrists are different since they focus on mental health rather than a specific physical organ system.

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