The main distinction between acute and chronic diseases lies in their duration and onset. Acute diseases are characterized by a rapid onset and short duration, often manifesting with severe symptoms but typically resolving completely after treatment. Examples include infections like the flu or a broken bone. In contrast, chronic diseases develop gradually and last for long periods, often for an individual's lifetime. They may have periods of exacerbation and remission, such as in conditions like diabetes or heart disease. Understanding these distinctions aids in appropriate treatment and management strategies.