The words chucker, chukker sound the same but have different meanings and spellings. Why do chucker, chukker sound the same even though they are completely different words?
The answer is simple: chucker, chukker are homophones of the English language.
One who chucks; a thrower.
A bowler who throws or chucks the ball rather than bowls it.
One of the periods of play, lasting 7 1/2 minutes, in a polo match.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License, 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").