The words competence, competents sound the same but have different meanings and spellings. Why do competence, competents sound the same even though they are completely different words?
The answer is simple: competence, competents are homophones of the English language.
The state or quality of being adequately or well qualified; ability. See Synonyms at ability.
A specific range of skill, knowledge, or ability.
Law The quality or condition of being legally qualified to perform an act.
Sufficient means for a comfortable existence.
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").