The words lade, laid, layed sound the same but have different meanings and spellings. Why do lade, laid, layed sound the same even though they are completely different words?
The answer is simple: lade, laid, layed are homophones of the English language.
To load with or as if with cargo.
To place (something) as a load for or as if for shipment.
To burden or oppress; weigh down.
To take up or remove (water) with a ladle or dipper.
Past tense and past participle of lay1.
Past tense and past participle of lay1.
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").