When one or more hydrogen atoms of a hydrocarbon are replaced by an equal number of hydroxyl groups (−OH group), the compound is called a hydroxy derivative.
The suffix −ol represents hydroxy derivatives.
Hydrocarbon and Hydroxy Derivative
Aliphatic (open-chained) hydroxy derivatives are called alcohols.
In phenols, the hydroxyl group of a hydroxy derivative compound is directly attached to benzene.
If the hydroxyl group is attached to a carbon chain which is attached to an aromatic ring, the compound comes under the category of alcohols.
Ethanol (CH3CH2OH) and normal phenol (C6H5OH) are used as antiseptics. Some alcohols and phenols are used in the manufacture of perfumes and flavors. For more theory, please refer to your book or wikipedia.