How are concave and convex lenses similar?

No. Convex lens bulge outward, and concave lenses go in ward. Convex lenses focus light, and concave lenses spread light out.

Concave and convex lenses are curved lenses that bend light in a predictable manner depending on their radius of curvature and index of refraction. A concave lens bend inwards and a convex lens bends...

They can be made from the same reflective material. They both are able to curve.

Both concave and convex lenses are used in glasses; A microscope, like a reflecting telescope, uses a concave mirror, a plane mirror, and a convex lens; A refracting telescope uses two convex lenses...

contact lenses are concave because their sides curve inward