Chapter 2, Problem 2.57P

Dimethyl ether $\left({\text{CH}}_{\text{3}}{\text{OCH}}_{\text{3}}\right)$ and ethanol $\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OH}\right)$ are isomers, but has $\left({\text{CH}}_{\text{3}}{\text{OCH}}_{\text{3}}\right)$ a $\text{p}{K}_{\text{a}}$ of $40$ and $\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OH}\right)$ has a $\text{p}{K}_{\text{a}}$ of $16$ . Why are these $\text{p}{K}_{\text{a}}$ values so different?