Functional isomers are compounds that have the same molecular formula but different functional groups. In the case of phenol and benzyl alcohol, they both have the same molecular formula, which is C6H6O, but they have different functional groups, making them functional isomers.

Phenol has the functional group -OH, which is known as a hydroxyl group. It is attached to a benzene ring, making it an aromatic alcohol. On the other hand, benzyl alcohol also has a hydroxyl group, but it is attached to a benzyl group, which is a CH2 group attached to a benzene ring.

Since phenol and benzyl alcohol have different functional groups, they cannot be classified as homologous compounds. Homologous compounds are a series of organic compounds that have the same functional group and similar chemical properties but differ in the number of carbon atoms in their molecular structure.

Phenol and benzyl alcohol also cannot be classified as position isomers. Position isomers are compounds that have the same molecular formula and functional group, but the functional group is attached to different positions in the carbon chain.

In conclusion, phenol and benzyl alcohol are functional isomers because they have the same molecular formula but different functional groups. They cannot be classified as homologous compounds or position isomers.