I'm going to give you my thoughts on this based off my own experience.

Being someone who was attacked, I was scared to death. Why? Because an un-assessed threat had attacked me without known provocation. It was out of pattern and routine. When other humans are out of pattern, it has the ability (at least for me) to up my adrenaline into fight or flight mode. Because any danger pre-programmed into our brains is a threat to our life. My response isn't predetermined and therefore will happen on the fly, so to speak.

Being the attacker, I knew what I was doing and I knew the possible outcome. Mentally, I had the resolve of not caring about possible consequences because this had to be done, for whatever reason. I didn't care anymore. I'd spent so much of my life afraid and wanting to run and hide....I was simply tired of being scared. That didn't mean the fear was gone but simply, my fear was morphed into a numb anger; just enough to do what I felt I had to do.

So, it's a sudden short-term fear vs. meditated long-term fear. That's the only real difference I experienced. Sorry if it doesn't make much sense.