I am not sure it is. Empathy is a character trait. A lot of people have empathy, but some not so much. People have more or less of all the various traits.
My mum could show sympathy and was a very loving caring mum but she had no empathy. She liked what she liked and she struggled with anything else. She couldn't understand people having ambition, sacrifing to put your kids though uni, wanting to divorce or having an age gap relationship, not feeling able to drop everything in your life to care for a relative, wanting to travel abroad, eating spicy/different food, going on holiday for more than a week, having lots of kids, moving away from where you grew up, wanting to go out on a week night rather that watch the soaps etc etc). She just could not put her self in someone elses shoes.
She once expressed to a neighbour how sad it was that their daugher had moved abroad. She was feeling sympathy for what was lost - which is how she would feel but she could not empathise. She could not see why the daugher would want to go or how her mum could be happy for her. She could not understand or share those feelings. She told me afterwards how sad it was.
In my marriage (which should have ended much sooner than it did), I used to feel for my husband if he was unhappy, even when he was being/had been a massive nob! If he was stressed, or angry, sorry or upset I would feel for him - often leading to me trying to be understanding or forgiving to my own detriment. When I was younger, friends would fall out with me for not taking sides if they fell out!