The words raiser, razer, razor sound the same but have different meanings and spellings. Why do raiser, razer, razor sound the same even though they are completely different words?
The answer is simple: raiser, razer, razor are homophones of the English language.
A person or thing that raises.
Someone who razes.
A sharp-edged cutting instrument used especially for shaving the face or other body parts.
A device for holding a razorblade, with guards to prevent cutting of the skin. Also called safety razor.
An electric instrument with vibrating or rotating blades used for shaving.
To shave, cut, or remove with or as with a razor: razored off the mustache; razored pages from a rare book.
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").