Professional indemnity insurance and public liability answer different questions, and one test separates them: was anybody hurt or was anything damaged. If yes, it is public liability. If the only loss is money, it is professional indemnity. Almost every real case resolves on that one distinction.
The test
Physical injury or damage to property belonging to somebody else means public liability. Pure financial loss caused by your work or advice means professional indemnity. A visitor tripping over your cable is the first. A client losing a contract because your report was wrong is the second.
How they respond differently
Public liability responds to events occurring during the policy period. Professional indemnity responds to claims first made during it, whenever the work was done. That is why professional indemnity must be kept continuous and public liability can be allowed to lapse once the activity stops.
Why most businesses need both
Very few businesses only touch property or only give advice. A consultant visits offices. A builder sometimes designs. A therapist has clients in a room. Client contracts name both because either alone leaves a hole on the side the client is most exposed to.
Questions people ask about professional indemnity insurance vs public liability
What is the simplest difference?
Public liability covers physical injury and property damage to third parties. Professional indemnity covers pure financial loss from your work.
Which one responds to a bad design?
Professional indemnity, because the loss is financial. If the design failure also caused injury, public liability can be involved too.
Can I have only one?
Yes, where your work genuinely only touches one side. Most businesses touch both and most client contracts require both.