What Is the Most Important Difference Between the Offences in Sections

What is the most important difference between the offences in sections 18 and 20 of the Offences Against the Person Act 1861?

A) Wounding is required for s. 20, but not s. 18.
B) Section 18 requires proof of a more serious injury.
C) Section 18 requires proof that the defendant intended to caused grievous bodily harm, but s. 20 only requires recklessness as to some harm
D) Section 18 requires proof that the defendant inflicted grievous bodily harm, section 20 requires proof that the defended caused grievous bodily harm.