The words yoke, yolk sound the same but have different meanings and spellings. Why do yoke, yolk sound the same even though they are completely different words?
The answer is simple: yoke, yolk are homophones of the English language.
To harness a draft animal to.
A crossbar with two U-shaped pieces that encircle the necks of a pair of oxen or other draft animals working together.
A pair of draft animals, such as oxen, joined by a yoke.
A bar used with a double harness to connect the collar of each horse to the pole of a wagon or coach.
The yellow, usually spherical portion of an egg of a bird or reptile, surrounded by the albumen and serving as nutriment for the developing young.
A corresponding portion of the egg of other animals, consisting of protein and fat that serve as the primary source of nourishment for the early embryo and protoplasmic substances from which the embryo develops.
A greasy substance found in unprocessed sheep's wool.
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").