What are the difference between concave lens and convex lens?

Chapter No. 7. Lenses,

What are the difference between concave lens and convex lens?


Concave Lens
Convex Lens
It is called diverging lens.
It is called converging lens.
This lens is thinner in the centre than at its edges.
This lens is thicker at the centre than at its edges.
The principal focus is virtual.
The principal focus is virtual.
The focal length is negative.
The focal length is positive.
This lens is used to correct myopia.
This lens is used to correct hypermetropia.