What is the difference between an Atom Bomb and Hydrogen Bomb?

An Atom bomb releases energy generated by the breaking apart of plutonium or uranium nuclei. A hydrogen bomb release energy created when atoms of an isotope of hydrogen are brought together. It takes an atom bomb, to create the conditions to operate a hydrogen bomb so a fission device is installed to trigger a fusion, or thermonuclear, explosion, duplicating conditions for a fraction of a second similar to those that go on at the center of our sun.