Ans. The difference between primary, secondary, and tertiary alcohols lies in the number of carbon atoms attached to the carbon atom bearing the hydroxyl group. A primary alcohol has one carbon atom attached to the carbon bearing the hydroxyl group, a secondary alcohol has two carbon atoms attached, and a tertiary alcohol has three carbon atoms attached. This classification is important as it affects the reactivity of alcohols. Primary alcohols are more reactive than secondary alcohols, which are in turn more reactive than tertiary alcohols, due to the ease of access to the hydroxyl group by reactants or reagents.