The fission process used in atom / nuclear bombs (no distinction in terminology) and reactors is the same process. In the bomb, the reaction is allowed to proceed in chain fashion with neutrons multiplying at each fission event in a runaway process. In the reactor, the neutrons are "moderated" to prevent a chain runaway, by absorbing them and changing their energy (temperature). Almost no uranium or plutonium is left over from a nuclear detonation (but there are fission products).
The fission process used in atom / nuclear bombs (no distinction in terminology) and reactors is the same process. In the bomb, the reaction is allowed to proceed in chain fashion with neutrons multiplying at each fission event in a runaway process. In the reactor, the neutrons are "moderated" to prevent a chain runaway, by absorbing them and changing their energy (temperature). Almost no uranium or plutonium is left over from a nuclear detonation (but there are fission products).