Dresses do not all look the same. They can be a multitude of colors. They can be long or short, maybe somewhere in between. They can be skintight or loose. They can have sleeves, spaghetti straps, even vests or jackets. Or they could have nothing. They can have sashes or belts or neither.
However, they also all have things in common.
They all cover the area from chest to at least a bit below the crotch (if they don't, it's not a dress). They all share that characteristic where they're, ah, open at the bottom. They're all considered clothing and are made from fabric.
They all have the same basic characteristics that make them dresses.
Stories, whether in book or script or poem or short form, are like this too. (Yes, this is another one of those posts where something is turned into an analogy for writing.)
No two stories are the same. They all have plot and characters and setting sure. But every one of those plots and characters and settings are different, even if only in the smallest way. And even if two plots or two characters or two settings were the exact same, the words describing them wouldn't be.
For instance, if I asked you to describe that purple dress over there, what would you say? (This is the hint for you to leave it in the comments so we can compare.) Here's mine:
Shades of purple fall in ripples down the fabric, losing their way and missing one arm.
Yours is probably very different from mine, but that doesn't mean it's not good. Just as two dresses can look nothing alike and yet both be pretty, you can be a brilliant writer without writing like J.K. Rowling or John Green. A dress could have ruffles or it could have lace. Your book could be paranormal or contemporary. And it would be wonderful either way.
Celebrate differences because without them I wouldn't have all these pretty dresses and the world wouldn't have so many awesome books.
Bonus dress analogy: Dresses look different (aka better) on various people and various people like different dresses. Various people will do better writing different genres and different genres will appeal to various people.
And I promise I'm not conceited. I just prefer to use pictures that are mine and not Google's.