differences - "Assailant" vs "Attacker"

Besides sports in which an attacker is an offensive player, is there any difference between assailant and attacker?

a person who attacks somebody

I guess attacker can also be used for animals but not assailant. Is there anything else or are they fully interchangeable when describing a person who physically attacks somebody else?

Can both words also be used when talking about psychological attacks, like insulting, bullying, etc?