"Empathy" in #NVC is a process where you connect to the feelings and needs of the other without judgment or assumptions, and you relate that back to them in a way that makes them feel heard. It is not a trait or a magic skill, it can be practiced and developed.
"Sympathy" is "relating to their experience by comparing it to your own". In very few situations, sympathy can be empathic, but in most it is not. It disconnects you from the other.