What is the difference between virtual and real images?

A  Virtual Image  is said to form where the light rays appear to meet but do not do so. We however can see a virtual image like the reflection in a plane bathroom mirror. It is supposed to be formed behind the mirror. Common example of virtual image would be the reflection in a plane mirror.

A Real image  is formed by actual meeting of light rays after hitting the optical system. In order to see a real image we require a viewing screen on which the light rays fall and form an image. So, we can indeed see real images but a screen in crucial for that. A very common example would be the image formed on a cinema screen