cashing, caching

The words cashing, caching sound the same but have different meanings and spellings. Why do cashing, caching sound the same even though they are completely different words?

The answer is simple: cashing, caching are homophones of the English language.

caching
  1. :: verb

    Present participle of cache.

cashing
  1. :: verb

    Present participle of cash.

Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License and Wordnik.

Share cashing, caching

About Homophones

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").