The largest KNOWN nuclear weapon was made by the Soviet Union (Russia) and was called the "Tsar Bomba" (King of Bombs). It had a yield of ~50MT.
The U.S.A.
35km
* Earthquake Richter 5.0 = 32 kilotons nuclear weapon, like was used at Nagasaki * Earthquake Richter 6.0 = 1 megaton nuclear weapon * Earthquake Richter 7.0 = 32 megaton nuclear weapon * Earthquake Richter 7.1 = 50 megaton nuclear weapon, Tsar Bomba, the largest nuclear weapon ever tested * Earthquake Richter 8.0 = 1 gigaton nuclear weapon, much larger than anything ever made
The meaning of the word nuclear weapon, is a weapon that has a nuclear warhead on it.
The largest nuclear bomb ever detonated was the Soviet Union's Tsar Bomba in 1961, which had a yield of 50 megatons. It was the most powerful nuclear weapon ever created and tested.
theoretically the yield of nuclear weapons is unlimited.
This nuclear weapon is called an atomic bomb or a nuclear bomb
An atomic weapon is an alternative name for a nuclear weapon, a weapon which derives its energy from the nuclear reactions of either fusion or fission.
Nuclear weapon detonations
If by "bomb" you mean a conventional explosive weapon, then the nuclear weapon is more powerful.
nuclear chemicals such as plutonium
That would vary from weapon to weapon.