Which statement best describes the difference between nuclear fission and nuclear fusion reactions?

Both fission and fusion are nuclear reactions that produce energy, but the applications are not the same. Fission is the splitting of a heavy, unstable nucleus into two lighter nuclei, and fusion is the process where two light nuclei combine together releasing vast amounts of energy

They are both nuclear reactions that produce energy.

Fission is the splitting of heavy, unstable nucleus into two lighter nuclei. Fusion is the process where two light nuclei combine together (this process releases a vast amount of energy)