Question

what are the general characteristics of real and virtual image

Answer 1

A real image can be photographed, captured on a screen or projected onto a screen.  The size of the image is either smaller than or equal to or larger than the size of the actual object.  That depends on the distance between the object and the mirror / lens.   The image is inverted (left to right or upside down).  The image is formed by converging rays.

A virtual image is formed inside a convex mirror or concave lens.  The image cannot be projected onto a screen.  The image is formed by divergence rays.  In case of convex mirror the image is smaller.