The words scents, sense, cense, cents sound the same but have different meanings and spellings. Why do scents, sense, cense, cents sound the same even though they are completely different words?
The answer is simple: scents, sense, cense, cents are homophones of the English language.
To perfume with incense.
To burn incense to.
Plural form of cent.
Plural form of scent.
Any of the faculties by which stimuli from outside or inside the body are received and felt, as the faculties of hearing, sight, smell, touch, taste, and equilibrium.
A perception or feeling produced by a stimulus; sensation: a sense of fatigue and hunger.
The faculties of sensation as means of providing physical gratification and pleasure.
An intuitive or acquired perception or ability to estimate: a sense of diplomatic timing.
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.
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").