The words polar, poler, poller sound the same but have different meanings and spellings. Why do polar, poler, poller sound the same even though they are completely different words?
The answer is simple: polar, poler, poller are homophones of the English language.
Of or relating to a pole.
Measured from or referred to a pole: polar distance; polar diameter.
Relating to, connected with, or located near the North Pole or South Pole.
Passing over a planet's north and south poles: a polar orbit.
One that propels, supports, conveys, or strikes with a pole.
A pole horse.
one who polls or lops trees
one who cuts hair; a barber
one who votes
one who registers voters or conducts a poll
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition, from Wiktionary, Creative Commons Attribution/Share-Alike License 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").