NPD is different, I went into it all long time back
EUPD is often difficulty managing a wide range of emotions (happy, sad, angry, love), their feelings can be very intense, and cause a lot of stress and anxiety for someone with EUPD. There is a lot of stigma with EUPD, women get diagnosed a lot more than men. Often with good stable support networks, people with EUPD can feel settled and secure and those feelings can be less intense (but raise up and down at times). I know with EUPD, relationships can be difficult, but ultimately these are very important to them and they seek validation, love and to feel secure.
NPD do not feel this wide range of emotions in the same way, or have the same anxiety. They do have fears, but they hide them, they are deeply insecure. They project their fears onto others, use them against others and they are more prone to deep deep rages, angry outbursts or harmful emotional behaviours like ignoring people in a way that causes them a lot of pain (this is why Alice things Ioan is narc because stonewalling is a very typical narc behaviour). They also believe they are superior, very special and important. Often their relationships will suffer because the cycles of rage/stonewall/inflated self importance becomes an abusive cycle no one can break free of.
Both are an experience of distortion of emotions, often in different ways. So someone with EUPD may believe they aren’t good enough to be loved, (so their loved ones may have to give a lot of validation) and someone with NPD may believe that they are so amazing and superior, they do not have to ever change or apologise for anything, even if this means losing the person that loves them - but deep down they do not want to lose them, so they will cycle through ways to keep hold of them, like an object.
I don’t want to offend. I think most people are on a spectrum of all these things, we all experience emotions differently and some people need assistance and support to manage them, and some just naturally manage better. I’ve had depression and anxiety most of my life, it is often triggered by stress. I think people with NPD lack empathy, and people with EUPD do not