What is the difference between atomic bomb and hydrogen bomb?

Answer 1

Actually the name atomic bomb includes the hydrogen bomb, all involve release of energy from atomic nuclei.

The actual difference is the nuclear reaction used to obtain the energy: nuclear fission and/or nuclear fusion.

There are actually many different ways these reactions can be used to produce practical atomic/nuclear bombs:

• pure fission devices - these were the original atomic bombs designed in ww2 and many designed since. they derive their energy entirely from fission.
• teller-ulam staged fusion devices - these are commonly called hydrogen bombs. they derive some of their energy from fission and some of their energy from fusion. However depending on certain details of their design they can derive anywhere from ~2% to over 90% of their energy from fission. they are built using a fission primary device to start the reaction and one or more fusion stages, ignited in succession by the stage immediately preceding them.
• boosted fission devices - these devices are high efficiency fission devices using a small amount of fusion fuel to generate extra neutrons, which "boost" the fission rate allowing either higher yield with the same amount of fissile material or a reduction in the amount of fissile material used with no loss of yield.
• dial-a-yield devices - these devices are variants of boosted fission devices using gaseous fusion fuel and a system permitting the soldier in the field to set just before use how much to add so that the yield can be varied to fit the current combat needs.
• neutron bombs - these devices are variants of the teller-ulam staged fusion devices that derive very little of their energy from fission (about 2% to 5%) and emit a high neutron flux. These have also been sometimes referred to as "clean bombs", particularly in the late 1950s although this term has gone out of fashion and is rarely used today.
• salted bombs - these devices are variants of the teller-ulam staged fusion devices that have certain elements added that when irradiated by the fusion neutrons produce highly radioactive isotopes, causing more deadly fallout. These have also been sometimes referred to as "dirty bombs", particularly in the late 1950s although this term has gone out of fashion and is rarely used today (they should not be confused with the modern usage of "dirty bomb", which is simply a conventional bomb wrapped in radioactive waste.). one such salted bomb commonly mentioned in fiction novels was the "cobalt bomb" as its salting element was cobalt, but it was never seriously considered as a weapon due to low efficiency of its production of radioactive cobalt-60. a "gold bomb" would actually work much better but be quite expensive.
• etc.