ICF is a type of fusion energy research that attempts to initiate a nuclear fusion reaction by heating and compressing a fuel target. Its normally in the form of a pellet that most often contains a mix of deuterium and tritium.
A nuclear reactor is a device used to initiate and control a sustained nuclear reaction. Nuclear reactors are used at nuclear power plants for electricity generation.
Compare: they are both nuclear, they both produce energy, they both are used at power plants.
Contrast: ICF uses fusion, while a nuclear reactor is used to control a sustained nuclear reaction.
This is all I can help with. By the way, are you in rocket science? 'Cause this stuff is hard.