With piglins and brutes having a similar attacking animation with vindicators, there is a slight difference between them. The motion of their arms while chasing something is different between piglins/brutes and vindicators.

It seems that the arm motion of the piglins and brutes are the same as the arm motion when they are idle and not doing anything.

To reproduce

1. Spawn a vindicator and a piglin (or piglin brute) with their movement speed attribute to 0.0d
2. Go to survival
3. Observe the motion of both of their arms