A fusion bomb, commonly referred to as a hydrogen bomb, utilizes nuclear fusion to release energy, whereas a fission bomb is known as an atomic bomb and relies on nuclear fission.

Both fusion and fission bombs are types of nuclear weapons that harness different nuclear reactions to generate enormous amounts of energy. The fundamental distinction between the two lies in the processes they employ: fission bombs operate through nuclear fission, while fusion bombs utilize nuclear fusion.

Nuclear fission is a process in which the nucleus of a heavy atom, such as uranium or plutonium, is split into two or more smaller nuclei along with several by-products. This reaction releases a substantial amount of energy but also generates significant radioactive waste. The first atomic bombs, which were deployed during World War II, were fission bombs.

In contrast, nuclear fusion occurs when two light atomic nuclei merge to form a heavier nucleus. This reaction, which powers the sun and other stars, releases even greater energy per unit mass compared to nuclear fission and produces considerably less radioactive waste. However, achieving the extreme conditions necessary for nuclear fusion is more complex than those required for fission. Typically, a fusion bomb employs a fission bomb as a trigger to attain the high temperatures and pressures essential for fusion to take place.

In terms of destructive capacity, fusion bombs are far more potent than fission bombs. The most powerful fusion bomb ever detonated, the Tsar Bomba, developed by the Soviet Union, had an estimated yield of $50$ megatons—over $3,000$ times more powerful than the bomb dropped on Hiroshima. This immense energy release is due to the fact that fusion reactions generate more energy per unit mass than their fission counterparts.

In summary, while both fission and fusion bombs are nuclear weapons that unleash tremendous energy, they do so through distinct nuclear reactions. Fission bombs operate by splitting heavy atomic nuclei, while fusion bombs achieve energy release by combining light atomic nuclei. Notably, fusion bombs are generally more powerful and produce less radioactive waste; however, they are also more challenging to construct.