The words pedal, peddle sound the same but have different meanings and spellings. Why do pedal, peddle sound the same even though they are completely different words?
The answer is simple: pedal, peddle are homophones of the English language.
A foot-operated lever used for actuating or controlling a mechanism, as in a loom, sewing machine, piano, or organ.
A similar foot-operated part attached to a crank and used for powering various devices, such as a bicycle.
Music A pedal point.
Music A pedal keyboard.
To travel about selling (wares): peddling goods from door to door.
To engage in the illicit sale of (narcotics).
Informal To seek to disseminate; give out: peddling lies.
To travel about selling wares.
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").