The stations use a variety of weather software systems which use the data available from the NWS and in some cases other reporting stations can also be used. They all do about the same thing, just how the graphics work seems to be the big difference.
What I find ridiculous is the NWS radar systems were all updated to DIGITAL Doppler, yet they continue to show radar "sweeps". Sweeps were part of the old analog systems and don't exist today. Even better is the "5 sweeps" using radar returns from Yuma, San Bernadino, Los Angeles and others that are beyond or at the limits for decent radar images (about 120 miles not including the mountains that block the signal). Yet you can watch "certified meteorologists" continue to use these graphics every day. (Guess it is supposed to make the viewers more comfortable that the information is accurate).