The words flour, flower sound the same but have different meanings and spellings. Why do flour, flower sound the same even though they are completely different words?
The answer is simple: flour, flower are homophones of the English language.
A fine, powdery foodstuff obtained by grinding and sifting the meal of a grain, especially wheat, used chiefly in baking.
Any of various similar finely ground or powdered foodstuffs, as of cassava, fish, or bananas.
A soft, fine powder.
To cover or coat with flour.
The reproductive structure of some seed-bearing plants, characteristically having either specialized male or female organs or both male and female organs, such as stamens and a pistil, enclosed in an outer envelope of petals and sepals.
Such a structure having showy or colorful parts; a blossom.
A plant that is cultivated or appreciated for its blossoms.
The condition or a time of having developed flowers: The azaleas were in full flower.
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").