Answer:
Both are nuclear reactions.
Step-by-step explanation:
Fission reaction: when a slow moving neutron strike with a heavy nuclei then it split up into two lighter and stable nuclei with the emission of three neutron and huge amount of energy is called nuclear fussion. e.g, U235 isoptope on bombardment of neutron split up into to two other stable nuclei.
Fussion reaction: combination of two or more nuclei to form another nuclei and evolve huge amount of energy is called fussion reaction. for example formation of helium nuclei.