Difference between concave and convex mirror

(1) The reflecting surface of the concave mirror is bulged inwards. But the reflecting surface of the convex mirror is bulged outwards.
(2) Concave mirror produces real and inverted images (except when the object is placed between pole and focus. When the object is placed between F and P, concave mirror produces virtual and erect image). But the convex mirror always produces virtual and erect images.
(3) The image formed by the concave mirror may be enlarged or diminished, according to the position of the object. The image formed by the convex mirror will be always diminished. 
LENSES

Convex lenses are curved outward and they cause light that goes trough it to converge or concentrate on one point. Think of a magnifying glass that is used to burn something. The light that goes through it concentrates on a point so you can burn things. Concave lenses are curved inward and when light goes through it diverges or spreads out. Think of a flashlight. The light comes from a small bulb goes through it and spreads out to a bigger beam on the other side.