The obvious difference is a plutonium weapon uses plutonium as its fuel while a uranium weapon uses uranium as its fuel, however there are also composite weapons that use both as their fuel.
Plutonium, being produced in reactors has some degree of plutonium-240 and plutonium-241 as undesired contaminates that can cause a fizzle. So weapons made with plutonium must be assembled much more rapidly than uranium weapons. So uranium weapons can use either gun or implosion rapid assembly systems, but weapons using any amount of plutonium must use implosion rapid assembly systems.
Reactor grade material is usable in most nuclear power plants. Weapons grade material is required for nuclear weapons. For uranium the difference between reactor grade and weapons grade is the level of enrichment: less than 20% uranium-235 is reactor grade, greater than 20% uranium-235 (greater than 90% is prefered) is weapons grade. For plutonium the difference between reactor grade and weapons grade is the level of contamination with plutonium-241: any amount of plutonium-241 is OK for reactor grade, only low levels of plutonium-241 are acceptable in weapons grade as its spontaneous fission rate can cause the bomb to fizzle.
Uranium or plutonium
Plutonium or Uranium .
No, plutonium is used more. Uranium can only be used in gun type nuclear weapons, which are rarely used.
Uranium and Plutonium
Plutonium is an artificial element; traces (extremely low) of plutonium isotopes of natural origin exist in uranium ores. Plutonium is used in nuclear weapons and nuclear fuels.
In nuclear weapons plutonium exist as metal or as an alloy Pu-Ga; in nuclear fuels plutonium is as dioxide (mixed with uranium dioxide) or carbide (also possible mixed with uranium carbides).
In the past, highly enriched uranium (cca. 99 % uranium 235); but now nuclear weapons generally have plutonium.
Spent uranium is used for armor piercing rounds. Enriched uranium is used in the production of plutonium that is used in the cores of nuclear weapons.
All modern nuclear weapons use plutonium. There may be a uranium component in some modern weapons as well, usually in the secondary or added on in rings to adjust the yield of the weapon.
Plutonium exist in ultratraces in uranium ores, in areas of nuclear weapons tests or near nuclear fuels recycling facilities.
Uranium 235 has 92 protons and electrons, 143 neutrons, atomic mass is cca. 235, is a natural isotope. Plutonium 239 has 94 protons and electrons, 145 neutrons, atomic mass is cca. 239, is an artificial isotope. Plutonium is more toxic than uranium. Also are differences in the types of radiations emmited, half-life and many other chemical and physical properties.