The words less, loess sound the same but have different meanings and spellings. Why do less, loess sound the same even though they are completely different words?
The answer is simple: less, loess are homophones of the English language.
Not as great in amount or quantity: had less time to spend with the family.
Lower in importance, esteem, or rank: no less a person than the ambassador.
Consisting of a smaller number. See Usage Note at few.
With the deduction of; minus: Five less two is three.
A buff to gray windblown deposit of fine-grained, calcareous silt or clay.
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").