Can you explain the difference between a real and a virtual image?

The ways in which these two things are experienced in real life is very different - you see a virtual image when you look through a lens or at a mirror, because light is coming at you as if it were coming from the object where you see it. But a real image isn't like that, you don't see it through the lens - a real image is formed at a particular point in space, and can be projected onto a screen (such as a white sheet of paper) that is placed there. The key difference in how this looks on a ray diagram is that a real image is formed at a point where rays from the object actually converge, whereas in the ray diagram for a virtual image there is no actual point of convergence of the rays - but there is a point of apparent divergence found by extending the emergent rays back as if there were no lens there.
So, a real image is a point of actual convergence, a virtual image a point of apparent divergence.