What is the difference between current and voltage?

Current and voltage are closely related properties of a circuit, one is caused by the other. What we refer to as voltage is in reality just a difference in charges, so, a difference in the amount of electrons between two places, say, two ends of a battery. Since electrons repel eachother, they will always try to flow to the place where there's less of them - this is current.

A good way to think of this is the "water analogy". We can think of a battery with voltage as one big water tank with high pressure and another with low pressure. When the two are connected, water will flow, with a bigger pipe corresponding to more water - just like a lower resistance corresponds to a higher current.