The words choir, quire sound the same but have different meanings and spellings. Why do choir, quire sound the same even though they are completely different words?
The answer is simple: choir, quire are homophones of the English language.
Any company of singers.
To sing in company.
An organized company of singers, especially one performing church music or singing in a church.
The part of a church allotted to the choristers; the choir.
A company or assembly.
See <xref urlencoded="choir">choir</xref>.
To sing in concert.
Definitions from The Century Dictionary., from The American Heritage® Dictionary of the English Language, 5th Edition., from the GNU version of the Collaborative International Dictionary of English. and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").