A homograph is one of two or more words of different meaning which are spelled in the same way. Homographs may be pronounced the same or differently. For example, the noun bear (the name of a large animal) and the verb bear (as in, I can’t bear this) are homographs which have identical pronunciation whereas the noun lead (the name of a metal) and the verb lead (as in, The Minister will lead the rally) are homographs with different pronunciation.

The noun principal and the adjective principal are also homographs.

He is the principal of the college.
He is the principal actor in the play.

Homophone

A homophone is one of two or more words of different meaning which are pronounced in the same way. Homophones may or may not have the same spelling.

For example the noun week (the period of seven days starting Sunday) and the adjective weak are homophones which are spelled differently whereas the noun bear and the verb bear are homophones which are spelled the same.

More examples are given below:

Hair and hare

Hair grows on our heads.
A hare looks like a rabbit.

Air and Heir

Air is everywhere.
He is the heir to the estate.

Hole and whole

Snakes live in holes.
I want the whole share.