The differences are important to understand,
The first thing to understand is that one of the main reasons consumer units (or fuse boards as they use to be called) are replaced is because yours doesn't have an RCD (Residual Current Device)
Why do I need an RCD? Well a Fuse or a Circuit Breaker is Designed to protect your installation and your assets (the cable in the wall and the cooker at the end of it) but a human cant take as much electricity as a cable or a cooker.
So we install an RCD, they are far more sensitive under earth fault conditions so if you or a family member are receiving an electric shock the power trips off quickly before it kills someone (that might not happen if you just had a fuse or a circuit breaker)
The Cheapest Option - Duel RCD
With this fuse board you get two RCD's and then several Circuit breakers that feed your circuits, like your sockets and lights.
This is fully compliant with the regulations and affords you the required level of protection, the only issue with this is if an earth fault occurs on one circuit, then all the other circuits that are supplied by that RCD also go off. And you cant turn them back on until the fault is resolved. An example of this could be your upstairs lighting circuit develops a fault, the RCD Trips as it should and as a result your kitchen sockets and your shower supply also go off, and until you get an electrician to resolve the faulty lighting circuit than you cant use your kitchen sockets or your shower. Example of a Duel RCD Board installed by us
See in the picture the 2 RCD's are the modules with blue and brown cables going into the top, look at the bottom the copper bar then links to the circuit breakers.
The Middle but slightly more expensive option - RCBO
RCBO stands for Residual Current Breaker & Overload essentially this is and RCD incorporated into a Circuit breaker.
Now the issues I spoke about with the cheapest option are no longer relevant because your faulty lighting circuit has its own circuit breaker and its own RCD so when it develops a fault only the lighting circuit goes off and you can still use your kitchen sockets and your shower.
The RCBOS you see below ensure every circuit has its own earth fault protection
The most expensive type - AFDD
AFDD Stands for Arch Fault Detection Device, this is a very new type of device that does all the jobs of a Fuse or Circuit Breaker, It also does the job of an RCD but it can also detect arching in a circuit, this is important because arching can cause fires. It is often caused by poor installation or damaged wiring.
These are very important for high ignition premise's (such as thatched buildings) the big issue at the moment though is price, because they are so new the manufacturers haven't yet brought the cost down.
A single AFDD will cost about about 10 times what and RCBO will cost and if your house has 6 or 10 circuits that's a huge cost increase, so an AFDD Fuse board alone without installation will currently cost well in excess of £1000 to purchase.
Example of an AFDD Consumer Unit by WYLEX