Revocable and irrevocable trusts get lumped together as "trust planning," but they solve fundamentally different problems, and the tradeoff between them — control versus protection — is the thing to actually understand before choosing.
A revocable trust keeps you in control
You can amend, revoke, or add and remove assets from a revocable trust at any time while you're competent. That flexibility is also its limitation: because you retain full control, the assets are still considered yours for creditor and estate tax purposes.
An irrevocable trust gives up control for protection
Once assets are properly transferred into an irrevocable trust, you generally can't take them back or change the terms unilaterally. In exchange, those assets can be shielded from creditors and removed from your taxable estate — protection a revocable trust doesn't provide.
Matching the tool to the actual goal
If the goal is avoiding probate and keeping things flexible, a revocable trust usually fits. If the goal is asset protection, Medicaid planning, or reducing estate tax exposure for a larger estate, an irrevocable trust — despite giving up control — is often the only tool that actually accomplishes it.
Many estate plans eventually use both
It's common for a plan to include a revocable trust for general asset management and probate avoidance, alongside a specific irrevocable trust for a particular protection or tax goal — they're not mutually exclusive, and the right structure depends entirely on what you're trying to solve.