Final answer:
Endergonic reactions require more energy to proceed, while exergonic reactions release more energy than the initial input.
Step-by-step explanation:
Endergonic reactions require more energy to proceed than the amount needed to get them started. These reactions are non-spontaneous and absorb energy. On the other hand, exergonic reactions release more energy than the initial energy input required to start them. These reactions are spontaneous and result in a net release of energy.