A proton and an electron are placed within a uniform electric field.

The magnitude of the electric force experienced by a charged particle in a uniform electric field $E$ is given by $F = |q|E$.

Since both the proton and the electron have the same magnitude of charge ($|q| = e$), they will experience electric forces of the same magnitude, $F = eE$.

The direction of the force on the proton is along the electric field, while on the electron it is opposite to the electric field. Hence, the forces are not equal as vectors.

The acceleration is given by $a = \dfrac{F}{m}$. Since the mass of a proton is much greater than the mass of an electron ($m_p \gg m_e$), their accelerations will be different in magnitude.