The most significant and practical differences between registered and unregistered design rights are that with a registered design:
You will have a longer fixed term of protection
It's irrelevant whether the person or business that copies your design is aware of your design or deliberately copies all or part of it. Registration gives you full monopoly protection, whereas with an unregistered design the position is potentially very different.
By registering your design you cut down on the evidence you need to present to the court in the case of an infringement, which saves on cost and reduces the issues that you need to prove. With a registered design, it is not necessary to show the design has been copied to establish infringement (whereas proving an opportunity to copy is an important issue in an unregistered design case) — this is a big advantage in any dispute making registered designs a worthwhile investment.