The words glair, glare sound the same but have different meanings and spellings. Why do glair, glare sound the same even though they are completely different words?
The answer is simple: glair, glare are homophones of the English language.
The white of an egg.
A sizing or glaze made of egg white.
A viscous substance resembling egg white.
To stare fixedly and angrily. See Synonyms at gaze.
To shine intensely and blindingly: A hot sun glared down on the desert.
To be conspicuous; stand out obtrusively: The headline glared from the page.
To express by staring angrily: He glared his disapproval.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.