What distinguishes circular road signs with a red border from circular road signs with a blue background in Brunei?

1. Red circular signs give prohibitions (what you must not do), while blue circular signs give mandatory orders (what you must do)
2. Red circular signs are optional suggestions, while blue circular signs carry criminal fines
3. Red circular signs apply only to commercial trucks, while blue circular signs apply only to private cars
4. Red circular signs indicate parking zones, while blue circular signs indicate speed limits