Question

What is the difference between convex and concave mirrors and lens ?

Answer 1

concave mirror 
has a curved in shape or structure.it goes in like a cave.
they are thinner in middle
they passing in rays spread out.i.e they diverge.
image formed is real and also virtual.
convex mirror
it has a bulging out structure
they are thicker in the middle
it will not let the rays diverge instead they converge.
the image formed is always virtual

Answer 2

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When an object is near a plane mirror, the image is erect, virtual and of the same size at the object. A concave mirror gives a magnified and erect image of a nearby object whereas a convex mirror gives an erect and diminished image. For the rear view mirror in a car.