Compare and contrast fission and fusion

Both require heat energy, while fission tears molecules apart, fusion "fuses" them together. Fission releases heat energy by splitting atoms. Fusion is actually what occurs on the sun.

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.