Alkanols and Alkoxyalkanes are

Alkanols are alcohols and Alkoxyalkanes are ethers. They are functional isomers:

Structure of ethanol:

${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{OH}$

Methoxymethane:

${\mathrm{CH}}_3-\mathrm{O}-{\mathrm{CH}}_3$

Both are functional isomers because they have same chemical formula but having different functional groups.