What is the main difference in using `RS^(Theta)` and `RO^(Theta)` as nucleophile in `S_(N)2` reaction?

Explanation

`RS^(Theta)` is a weak base, while `RO^(Theta)` is a strong base. Therefore, when `RS^(Theta)` is used as a nuclephile in an `S_(N)2` reaction, the elimination (E2) reaction is not a major problem. However, when `RO^(Theta)` is used as a nucleophile, an elimination reaction is a major problem.