The words intense, intents sound the same but have different meanings and spellings. Why do intense, intents sound the same even though they are completely different words?
The answer is simple: intense, intents are homophones of the English language.
Possessing or displaying a distinctive feature to an extreme degree: the intense sun of the tropics.
Extreme in degree, strength, or size: intense heat.
Involving or showing strain or extreme effort: intense concentration.
Deeply felt; profound: intense emotion.
Plural form of intent.
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.