If the Christmas lights are arranged in a parallel circuit then when one bulb burst (is removed) the other light bulbs _will_ light up.
It limited the reach, it skipped over and went to the other light. The light is bright cause one light is getting all the energy.
If the Christmas lights are arranged in a series circuit then when one light burst the other bulb _will not_ light up
Zero light bulbs came on. The energy lost the connection so no light came on.
A parallel circuit is the best series to use for Christmas lights because it works around the not working lights. And lets everything else work among the lights.