= Solution
Fission divides a heavy nucleus into more tightly bound fragments, releasing <energy> through the increase in <binding energy per nucleon>. A neutron-induced chain reaction can sustain <heat> production in a controlled reactor. Fusion combines light nuclei into more tightly bound products and needs sufficiently high <temperature> and confinement to obtain a useful reaction rate despite Coulomb repulsion. Both ultimately supply <heat> that must be converted to electricity, unless a different energy-conversion scheme is explicitly introduced.
A typical fission releases about $200$ MeV per event, corresponding to roughly $8\times10^{13}$ J per kilogram of fully fissioned heavy fuel. The deuterium-tritium fusion <energy> of $17.6$ MeV per reaction corresponds to about $3.4\times10^{14}$ J per kilogram of reacting mixture. These are <nuclear reaction> energies, not electricity per kilogram of mined or engineered fuel. Actual fuel use, thermal efficiency, parasitic <power> and incomplete burn change plant output.
Fission has substantial operating experience and can provide high-capacity-factor generation, but faces capital, waste, decommissioning, fuel-cycle and safety constraints. Fusion avoids a self-sustaining <neutron> chain reaction in the fuel, but its systems still face <neutron> damage, activated materials, tritium management and demanding <heat> extraction. Demonstrating a hot <plasma> or a favorable reaction-energy balance is not the same as demonstrating economical net electricity. The useful comparison distinguishes scientific feasibility, engineering availability and whole-system cost.
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