How do the spectra of the other elements compare with the spectrum of a light bulb and the spectrum of hydrogen?Why is the light that is emitted by...

Hydrogen is the simplest atom with one electron. The
electron in cold hydrogen is in its "ground state" which means it is orbitting as close
to the nucleus as it can get. The electron can be given energy by heat, electricity etc.
This can cause it to move away from the nucleus or jump to a higher "orbit". This is
called excitation.

Satellites orbiting the Earth can make
an almost infinite series of small increases in orbital radius but electrons cannot do
that due to quantisation of energy at these microscopic sizes. This means that the
electron can only ocupy certain discreet orbits.

An excited
electron in hydrogen may jump to any "allowed' orbit (properly called orbital) and may
fall straight back to the ground state when the energy it gained to make the jump is
released as a single photon of definite frequency and hence colour. Or it may fall
through any permutation of orbitals releasing photons of other frequencies. This is the
cause of the line spectrum seen in a spectroscope. A neat homemade spectroscope can be
made from a CD disc.

Every other element does this but
because there are different numbers of electrons and different nuclear charge affecting
their allowed orbitals they produce different line
spectra.

Tungsten filament lamps (globes) emit a seemingly
continuous spectrum similar to a rainbow because of the much larger number of electrons
emitting a very large number of close frequencies. Individual lines can be resolved with
a suitably sensitive spectroscope. This routinely done with
starlight.

One useful element for economical street lamps
is sodium (as an excited vapour) which has a particular electron transition (jump) that
produces a bright yellow light.

Some types of street lamp
use mercury vapour which emits UV photons that then excite a fluorescent material to
emit visible light.