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How did the bomb dropped on Hiroshima differ from the bomb dropped on Nagasaki?

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U.S. hydrogen bomb test in the Marshall Islands — nuclear weapon A test of a U.S. thermonuclear weapon (hydrogen bomb) at Enewetak atoll in the Marshall Islands, November 1, 1952.

The atomic bombs dropped on Hiroshima and Nagasaki differed significantly in their design, fuel, and explosive power.

Little Boy (Hiroshima): Dropped on August 6, 1945, this bomb utilized a gun-type assembly design. It functioned by firing one piece of uranium-235 into another to achieve a critical mass. It was an untested design at the time of its deployment and had an explosive yield equivalent to approximately 15,000 tons of TNT.12345
Fat Man (Nagasaki): Dropped on August 9, 1945, this bomb used a more complex implosion-type design. It featured a core of plutonium-239 surrounded by high explosives that, when detonated, compressed the core inward to reach a supercritical state. This design was tested previously during the Trinity test and was more powerful than Little Boy, with an explosive yield of 21,000 tons of TNT.1254

While both weapons caused catastrophic destruction and loss of life, the differing terrain of the two cities also influenced the extent of the damage, with Nagasaki’s irregular landscape limiting the spread of fires compared to Hiroshima.65