Nucleat fallout is the radioactive particles that fall to earth as a result of a nuclear explosion; examples are toxic gas leak, acid rain and nuclear explosion while a natural disaster is a sudden event caused by environmental factors and natural processes of the Earth; examples are floods, hurricanes, tornadoes, volcanic eruptions, earthquakes, tsunamis.
Both are highly dangerous. It is difficult to tell which more deadly. The severity of each event determines how deadly it will be.
Both are equally as dangerous. Some human-made disasters include acid rain, nuclear explosion, and gas leak. These are harmful enough to kill millions of people. The after effects of man-made disasters last longer than that of natural disasters.
An example of a terrible human-made catastrophe is the vast oil spill in the Gulf of Mexico, which was harmful to both people and wildlife; however, natural disasters tend to be larger in size. There is also no warning when there is a natural disaster. Communication channels and significant infrastructure are diminished or eliminated when there is a natural disaster. Examples of natural disasters include earthquakes, tsunamis, and tornadoes.