Final answer:
Nuclear fission involves the splitting of a large nucleus with the release of energy and has the potential for a chain reaction, while fusion combines light nuclei to form a heavier nucleus and generally releases more energy than fission.
Step-by-step explanation:
Nuclear fission and fusion are processes that involve changes in the nucleus of an atom. In nuclear fission, a large unstable nucleus absorbs a neutron and splits into two smaller nuclei along with additional neutrons and a massive amount of energy. This process can create a nuclear chain reaction if there is a critical mass, where emitted neutrons from fission induce further fissions.
Nuclear fusion, on the other hand, occurs when two light nuclei combine to form a heavier nucleus, releasing energy in the process. This energy release is due to a small amount of mass from the reactant nuclei being converted into energy, according to E=mc^2. The most significant example of fusion is the reaction that powers stars, where hydrogen nuclei fuse into helium, releasing energy.
To compare the amount of energy released, fusion typically releases more energy than fission. The fusion of hydrogen into helium releases around four times more energy than the fission of uranium-235, which is commonly used in nuclear reactors.
A diagram or model representing nuclear fission would show a large nucleus, like Uranium-235, absorbing a neutron and then splitting into two smaller nuclei, releasing additional neutrons and energy. For fusion, a diagram would illustrate two hydrogen nuclei merging to form a helium nucleus while emitting energy.