I'm no lawyer and I'm not very smart, so I hire people to advise me. I have 2 LLCs, 2 S-Corps, and I'm 49.5 owner in a Limited Partnership and carry 5 million umbrella.
It has been explained to me like this, "inside" and "outside" protection.
Outside- Protecting YOU and your personal assets from your property. LLCs, trusts, and Limited Partnerships can provide this protection. They can also provide protection from different businesses owned all or in part by you. Example: Accident happens and a lawsuit is judged against your LLC, only assets inside that LLC could be forfeited in settlement. That's why most investors limit there equity in each LLC
Inside protection- Protecting your Corporation or shares from you. Example: An accident at your residence results in a lawsuit judgement against YOU. If that judgement is more than the maximum coverage of your homeowners policy Your assests, shares, and corporations could be seized or awarded in judgement. A PULP (personal umbrella liability policy) would kick in over the maximum of your homeowners(or auto, RV, etc) insurance up to your umbrella policy limit.