What is the difference in the reaction that proceeds when we use the reagent $\ce{C2H5O- Na+}$ and $\ce{NaOH}$ in $\ce{C2H5OH}$ in with, say ethyl chloride. Is the latter considered to be "alcoholic NaOH"?
$$\ce{CH3-CH2-Cl}$$
As per my understanding, $\ce{OH-}$ in $\ce{C2H5OH}$ exist in an equilibrium with $\ce{C2H5O-}$ and $\ce{H2O}$, with the formation being favoured due to a basic medium provided by $\ce{NaOH}$ $$\ce{C_2H_5OH + OH- <=> C_2H_5O- + H2O}$$ $$\ce{C_2H_5O- + CH_3-CH_2-Cl -> C_2H_5OC_2H_5}$$ $$\ce{C_2H_5O- + CH_3-CH_2-Cl -> CH_2=CH_2}$$ Given that the substrate is a primary chloride, nucleophilic substitution by $\ce{C2H5O-}$ seems to be the most favourable pathway, as compared to E2-elimination. (Williamson synthesis)
However, I have seen in multiple books that both alkenes/ethers are given as products in different instances, with the reagents I mentioned being used interchangeably. What is the difference between them and what is the major product formed?