Here is your 10-point fact sheet on why the hydrogen bomb is more dangerous:
A Hydrogen bomb is a much more powerful atomic weapon.
The energy released in a Hydrogen bomb is several magnitudes higher than an Atom bomb. Hydrogen bombs can devastate whole cities in one explosion.
A Hydrogen bomb derives its energy through the fusion of atoms. An Atom bomb derives its energy from fission.
Nuclear fusion and nuclear fission are different types of reactions that release energy. In fission, an atom is split into two or more smaller, lighter atoms.
Fusion, in contrast, occurs when two or more atoms fuse together, creating a larger, heavier atom.
Hydrogen bombs use the fusion of hydrogen atoms, hence its name.
A fusion bomb is more sophisticated and difficult to make, since it requires a much higher temperature -- in the order of millions of degrees centigrade. So a fission is carried out first to produce more energy, which is then used to initiate fusion. In a fusion bomb, a fission device has to be triggered first.
It is easier to make Hydrogen bombs in small size, so it is easier to place them in missiles.
Hiroshima and Nagasaki both were atomic bombs and till date Hydrogen bombs have never been used in war.
This is the fourth atomic test by North Korea and its first fusion bomb.