Having a debate on whether "You are being a jerk" and "You are a jerk" have the same meaning in context. Are you calling someone a jerk if you state they are "being" a jerk or is the context that they are portraying qualities of a jerk?
There is a pretty visible distinction between both, and this example displays one of the main uses of continuous present.
You are being a jerk
Means that you're a jerk right now, on the matter at hand.
You are a jerk.
Is way more general and is used to express your opinion about the person. However, you could say "you're such a jerk" on the moment because you're furious, but then not think so any more.
You are being a jerk.
He/she is not a jerk, but at that time he/she is acting like one. Or portraying the qualities of a jerk.
You are a jerk.
It's a fact. The person is a jerk. This can also mean that the person is acting like a jerk at the time of speaking. Without context, it's not really possible to determine whether they have different or same meaning.
Saying "You are" implies a quality that is deeply engrained in someone or rather a quality they have little to no control over and/or unable to change on demand. Whereas saying "You are being" implies a quality that one could easily change at will.
Sometimes you can't refer to someone as "being", such as if you were to say, "You are tall." You couldn't say, "You are being tall" because that is not a quality that someone can easily change. Saying of someone "You are a jerk" would be more insulting than saying "You are being a jerk".
"You are being" is happening right now. The targeted individual is presently behaving the way described.
- You are being silly. -- They are doing something silly right now.
- You are being mean. -- They are doing something mean right now.
- You are being argumentative. - They are being argumentative right now.
"You are" is what the targeted individual is in a broad, constant sense.
- You are silly. -- They aren't behaving in a silly way, they are a silly person.
- You are mean. -- They aren't being mean, they are a mean person.
- You are argumentative. -- They aren't arguing, they are an argumentative person.
Imagine two people side by side, one a selfish Jerk and one who is compassionate. Either one has the option of acting out a quality of the other, compassionate can be (are being) a jerk or selfish and the Jerk, although a Jerk, can be compassionate. "Are being" or "being" does imply acting out "right now" and the implication is that you are still what you started out as.