A real image is displayed on a screen like a picture in a movie theater. Usually with concave mirror and convex lens the real image is formed inverted - upside down.
The real image is actually formed where the rays emanating from each point on the object converge after reflection or refraction, and meet at one point on the image.
Virtual image is formed when the rays from each point appear to diverge from a point, after reflection or refraction. Actually, in reality, there is no picture formed. Our mind and eyes imagine the image to be there.
In sign conventions, real image has negative magnification and virtual image has a positive magnification.
Virtual image is erect or upright and real image is inverted.