what is the difference between mirror and lens

mirror -image is formed after reflection and in lens it forms after refraction

A mirror is a reflective  surface. Light passes through the glass and hits the silver 
backing, reflecting off of it. (The angle of incidence equals the angle of reflection.) Mirror are - convex, concave and plane.

A lens, on the other hand, does not reflect light; it refracts it. After entering the 
glass, light refracts differently depending on the shape of the lens and also 
creates a focal point where the refracting light comes to a point. This differs for 
different lenses -- convex or concave -- which is why there are different lenses for 
different types of eyeglasses.