The words canter, cantor sound the same but have different meanings and spellings. Why do canter, cantor sound the same even though they are completely different words?
The answer is simple: canter, cantor are homophones of the English language.
To go or move at a canter.
A smooth gait, especially of a horse, that is slower than a gallop but faster than a trot.
To ride a horse at a canter.
To cause (a horse) to go at a canter.
The Jewish religious official who leads the musical part of a service.
The person who leads a church choir or congregation in singing; a precentor.
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.
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").