What’s the difference between “you’re not” and “you aren’t “?

To add to the other comments, sometimes we choose which word to contract because we want to accentuate something. The sample above doesn't do a great job of showing this, so here is another example: "You are not going in there." - maybe this is from a horror film for example. With the examples below, tgere is added vocal emphasis on the capitalized word. Without the added emphasis, there is no change in the meaning of the sentence from a simple statement. "YOU aren't going in there." - Highlights You in the sentence. This implies the reason you aren't going in there is either because someone else is, or because the speaker cares about you too much to allow you specifically to go, but someone else could. "You're NOT going in there." - An emphasis on Not highlights the denial. Maybe they are incredulous (disbelieving, surprised) that you would suggest it. Maybe they are enforcing a rule that no one is allowed in. For this version, the person in particular doesn't matter. The denial is the same for anyone. With contractions, you cannot emphasize the contracted word. It's why we don't end sentences with contractions usually. We also don't contract the subject as often when the subject is important (sometimes still happens, especially if the verb is equally important, such as "I'M going in there, and YOU'RE not gonna stop me.").

There is none. They are both contractions of "You are not," just contracting different parts of the phrase.

They're interchangeable

One emphasize you. One emphasize not.

There's no difference in meaning. We typically say "you're not yourself" only because the "r-n-t-y" cluster in "you aren't yourself" is awkward to pronounce.

Nothing. Sometimes one sounds better than the other depending on how the sentence is structured but other than that they're both contractions of "you are not" and are exactly the same

Let’s not forget “y’ain’t”

"You're" = You are You're not yourself = You are not yourself. "Aren't" = Are not You aren't yourself = You are not yourself. They're the same and both are correct to use!

Zero difference.

They're the same, no difference in connotation.

I say You’re not more often than you aren’t. But it’s regional. Aren’t is replaced with ain’t in many places too. My region it’s you’re not.