Real images versus virtual images – Concave lens
The main difference between a real image, and a virtual image and the statement you need to remember, is:
A real image can be displayed on a screen
A real image can be displayed on a screen or piece of paper or on a wall, whereas a virtual image can not.
A virtual image can be seen with the eyes but you can not display the image on a screen. It's not possible.
With a convex lens the light from an object passing through the lens can be projected on to a screen.
With a concave lens only a virtual image can be seen. At no point can an image be projected or captured on a screen.
Notice, too, that with lenses:
Real images – always inverted
Virtual images – always upright
A real image is always inverted whereas a virtual image is always upright.