Homographs are a kind of homonym in the loose sense of that term, i.e. a word that is either a homophone (same sound) or a homograph (same spelling). (The strict sense of homonym is a word that both sounds and is spelled the same as another word.) Specifically, homographs must have the same spelling, though they usually have different meanings and may be pronounced differently.
The verb bear(“to carry”) and the noun bear(“large omnivorous mammal”) are homographs with the same pronunciation and different etymological origins.
The verb alternate(“to go back and forth”) and the adjective alternate(“following by turns”) are homographs with different pronunciations but close etymological origins. Such homographs are also heteronyms.
The verb meet(“to encounter”) and the noun meat(“food”) are not homographs since they have different spellings.