In chemistry|lang=en terms the difference between ethoxide and methoxide

is that ethoxide is (chemistry) any salt of this anion while methoxide is (chemistry) any salt of this anion.

As nouns the difference between ethoxide and methoxide

is that ethoxide is (chemistry) the anion ch₃ch₂o⁻ derived from ethanol by the loss of a proton while methoxide is (chemistry) the anion ch₃o⁻ derived from methanol by the loss of a proton.