What are the features of nuclear fission bombs and nuclear fusion bombs?You can tell about these types of nuclear bombs. But features are must.

A nuclear fission bomb uses two main features: first, that
uranium is a radioactive material which spontaneously breaks down into two smaller
elements, at the same time releasing a small amount of energy and two or more
neutrons.

Second is the concept of a chain reaction. In a
chain reaction a neutron strikes the nucleus of a uranium atom causing it to split,
releasing two or more additional neutrons. Each of these neutrons can then hit other
uranium atoms causing them to split and release even more
neutrons.

So start with one neutron hitting one nucleus and
then releasing two neutrons.  These two neutrons hit two more nuclei releasing a total
of 4 neutrons, which hit 4 more nuclei, releasing 8 neutrons, and very quickly you have
a very large number of uranium atoms being split.

In a
nuclear power plant this chain reaction process is controlled so only a certain number
of neutrons are flying around at a time. In a fission bomb a number of pieces of uranium
are brought together all at once and an uncontrolled chain reaction occurs, releasing a
tremendous amount of energy all at once.

A fusion bomb
works on the principle that if you force the nuclei of two small atoms close enough
together, you can overcome the natural repulsion between their positive charges and form
a new, larger element.  Thus, if you combine two hydrogen atoms, you can make a helium
atom.  In the process of fusing the two atoms a small amount of energy is also
released.

Fusion is a much more difficult process to
achieve because it requries very high temperatures and pressures to force atoms to join
together. In fact, a fission bomb may be required to provide enough energy for the
fusion, or hydrogen bomb, to ignite.

In summary - a fission
bomb relies on the natural, spontaneous breakdown of large radioactive elements,
especially uranium, into smaller elements through a chain reaction. You can't stop
fission from occuring but you can control how fast it
happens.

A fusion bomb requries large amounts of energy and
very high pressures and is not a natural process on earth. You have to force it to
ignite.