What's the difference between reassign and delegate?

A user can reassign the task to another user for approval. The new user's hierarchy is used for approval. For example, if a user receives an approval request relevant to another team, he can reassign it to a user in another team.

A user can delegate a task to another user, who can act on the user’s behalf. The original user’s approval hierarchy remains unchanged. If the task expires before it is completed, the delegate can still take the available action on the task.

For example, if an approver delegates a task to a colleague while away, that colleague can still approve or reject the task even after its due date has passed.