How are allylic alcohols different from benzylic alcohols?

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The primary difference between allylic and benzylic alcohols lies in the structural environment of the carbon atom to which the hydroxyl group is attached.

Allylic alcohols: These are defined as alcohols in which the hydroxyl group is bonded to an allylic carbon atom, which is a carbon atom located immediately adjacent to a carbon-carbon double bond (C=C).1
Benzylic alcohols: These are defined as alcohols in which the hydroxyl group is bonded to a benzylic carbon atom, which is a carbon atom located immediately adjacent to a benzene ring.1

In both cases, the classification is based on the specific functional group or structural feature—either an alkene or an aromatic ring—that is positioned next to the carbon bearing the hydroxyl group.1