Homophones are words that are pronounced alike but their spellings or meanings are different.
For example; to, too and two/ hair, hear and here/ there and their
Homographs are words that are spelled alike but mean different.
For example, Bear (to endure) and Bear (animal)/ Park (a large public garden or area of land used for recreation) and Park (bring (a vehicle that one is driving) to a halt and leave it temporarily, typically in a car park or by the side of the road)
Homonyms are words that are either homographs or homophones. It is said that homonyms should be restricted to words that spell alike and have different pronunciations and meanings.
For example: "No" and "know" are homonyms. "Bow" (bend at the waist) and "bow" (weapon) are also homonyms.