Answer:
If we have only one path, this means that the circuit is connected in series, one light bulb after the other, the current decreases a bit of intensity when it passes through the first light bulb and reaches the other with less intensity, so in this case, you may see that the first one brights more intensely than the second one, if there is a remanent of current, it goes again to the battery. In the parallel case, we have a bifurcation of the path, where the current divides into both paths and each part goes to a single light bulb, here we will see both light bulbs shine with the same intensity.
so the paths are:
Series:
battery----light bulb--- light bulb---battery
Parallel:
light bulb
battery---< >-------battery
light bulb
