The line used by helium neon lasers, 632.8 nm wavelength, does not appear in the spectrum of a neon tube. It is too dim relative to the other lines. The lines of light are produced when electrons in an excited state decays into a lower energy state. The change in energy of the electron between these two states is precise and results in the emission of light with a narrow range of energies, a spectral line. Sunlight Look at sunlight by looking at a white surface in the sun.
White paper works well.
The solar spectrum is a continuous spectrum of an incandescent gas. Look closely and you will see fine dark lines crossing the solar spectrum. These fine lines are fraunhofer lines. The dark lines are produced by gas above the surface of the sun which absorbs some of the incandescent light from the sun below. Each of these lines is produced by one atom or ion.