Image 1: This is an image of of a series circuit. There is one, equal current running through the whole circuit. The voltage remains the same throughout the whole series circuit. This is because there are no resistors, and in a series circuit, the voltage always remain the same.
Image 2: This is an image of a complex circuit. In this circuit, I have a parallel circuit, and a series circuit. The voltage is different in this circuit. The 1 light bulb in the series circuit is brighter than the 2 light bulbs in the parallel circuit because it has more voltage. The two light bulbs in the parallel circuit have the same voltage. The current in the parallel circuit is different to the current in the series circuit because it has more resistors.
Image 3: This image is of a parallel circuit. In this circuit, the voltage is the same between the two light bulbs. The current is the same in the parallel circuit. The current is equal to the voltage divided by the risistance. Since the voltage and resitance of both light bulbs are the same, the current is the same.