why do concave lens have greater divertion than convex lens?

A concave lens is thinner in the middle and thicker at the edges so the incident rays  after refraction are appear to diverge from a point on the principal axis. while the convex lens is bulge out at centre than the edges, so the incident rays after refraction are convege to a point on the principal axis. because of peculiar shape the concave lens have greater diversion than the convex lens.