InsanityRanch has given a good explanation.
Just to add to it, think about English:
I can say "beautiful." I can also say "admirable, alluring, angelic, appealing, attractive, beauteous, bewitching, charming, classy, comely, cute, dazzling, delicate, delightful, divine, elegant, enticing, excellent, exquisite, fair, fascinating, fine, foxy, good-looking, gorgeous, graceful, grand, handsome, ideal, lovely, magnificent, marvelous, nice, pleasing, pretty, pulchritudinous, radiant, ravishing, refined, resplendent, shapely, sightly, splendid, statuesque, stunning, sublime, superb, symmetrical, taking, well-formed," or "wonderful."
Now, why would we have so many words that basically mean the same thing?
It's called "nuance of meaning," and it exists in every language. Believe me, I understand your pain. Just the other day I ran across several different words that all mean "cooperation."
共同、協同、恊働、協力、協調、連携、互助
The fun part is asking a Japanese person to explain the difference in nuance between these words. Imagine trying to explain to someone who doesn't speak English all the different synonyms for "beautiful."
