With a will, the court-supervised process will pass your assets through a will (if without a will, through state law), and it can still be time consuming and expensive.
With a trust (the most common is a revocable living trust), you can not only avoiding probate but ensuring your assets go to the people you choose.
In Short
With a will, the executor is just kind of an administrator who transfers assets from one person to another. With a trust, a trustee is more of a decision maker, they stand in your shoes and make decisions you would want to make if you were still around to make them.