The heart of the matter

Abusive leadership is not defined by obvious harsh behaviour, and servant leadership is not about literally performing servant tasks, as shown clearly in the life and ministry of Jesus.
Jesus did not take on the literal role of a servant, and even acts like washing the disciples’ feet were exceptional, showing that servant leadership is not about role but about heart.
The essence of servant leadership is seeking what is best for followers in the purposes of God rather than seeking personal benefit, as modelled by Jesus and Paul.
In contrast, the essence of abusive leadership is using followers for personal gain, often through manipulation, selfish ambition, greed, and self-promotion, even while appearing kind.
A servant leader may be firm but leads for the true good of people, while an abusive leader flatters and exploits, leaving each leader to choose whether to serve others or themselves.