The words real, reel sound the same but have different meanings and spellings. Why do real, reel sound the same even though they are completely different words?
The answer is simple: real, reel are homophones of the English language.
Being or occurring in fact or actuality; having verifiable existence: real objects; a real illness.
True and actual; not imaginary, alleged, or ideal: real people, not ghosts; a film based on real life.
Of or founded on practical matters and concerns: a recent graduate experiencing the real world for the first time.
Genuine and authentic; not artificial or spurious: real mink; real humility.
A device, such as a cylinder, spool, or frame, that turns on an axis and is used for winding and storing rope, tape, film, or other flexible materials.
A cylindrical device attached to a fishing rod to let out or wind up the line.
The quantity of wire, film, or other material wound on one reel.
A set of curved lawn-mower blades that rotate around a bar parallel to the ground, cutting grass while moving against a stationary straight blade.
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").