The words spoor, spore sound the same but have different meanings and spellings. Why do spoor, spore sound the same even though they are completely different words?
The answer is simple: spoor, spore are homophones of the English language.
The track or trail of an animal, especially a wild animal.
To track (an animal) by following its spoor or to engage in such tracking.
A small, usually single-celled reproductive body that is highly resistant to desiccation and heat and is capable of growing into a new organism, produced especially by certain bacteria, fungi, algae, and nonflowering plants.
A dormant nonreproductive body formed by certain bacteria in response to adverse environmental conditions.
To produce spores.
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").