Fission and fusion are alike in many ways. however, one difference is

Fission and fusion both fit in the same category, dealing with nuclear reaction for energy production. There is, however, one big difference between the two. Fission involves splitting and fusion involves combining. If a large mass of energy breaks apart, fission, it form several smaller parts, sparking more energy. During fusion, several components can combine and make a much larger mass, this can create large objects, such as the sun, that form under extreme pressure.