North Korea claims to have tested a hydrogen bomb recently.
Hydrogen bomb is more deadly than Atomic bomb, the bomb that devastated the Japanese cities of Nagasaki and Hiroshima during World War II.
Atomic (nuclear fission) bomb and Hydrogen bomb (nuclear fusion + fusion) are both nuclear bombs.
Hydrogen bomb is so powerful that it needs an atomic explosion to kickstart its own explosion.
The bombs dropped on Hiroshima and Nagasaki exploded with the yield of 15 kilotons and 20 kilotons of TNT, respectively, according to the Union of Concerned Scientist.
In contrast, the first test of a hydrogen bomb, in the United States in November 1952 yielded an explosion on the order of 10,000 kilotons of TNT.
TNT stands for Trinitrotoluene. It is the most powerful non nuclear bomb.