Question

difference between umbra and penumbra

Answer 1

There are two parts to these shadows. The umbra is a central cone of darkness which tapers away from the Earth or Moon, whilst the penumbra is an outer cone of partial shadow which diverges instead of tapering. The Moon's shadow cast on the Earth appears as a solar eclipse.

Answer 2

umbra= dark part of the shadow that does not receive any light
penumbra = less dark part of the shadow around the dark shadow