The only difference is that rather than a DHW heating coil in the cylinder it has a ( third ) pump to run the store contents through the plate HE.
And more sensors, and more PCB logic, and more software.
More complication than a DHW heating coil in the store and more cost I would have expected with no significate benefit.
Descaling is easier.
Diagnosis is easier.
The 2000 is more reliable.
Those benefits are significant, IMHO.
Whilst good in their day, the expectation of storing water at 80°C is not compatible with efficient condensing boiler operation.
More like 72-75°C, and it's an off-topic point anyway.
The advantages are clear. The Boilermate, learns the boilers maximum heat output and runs accordingly. It is self adaptive. It also learns how long it takes the boiler to reheat the cylinder to bring it in at the right moment. It even uses the DHW pump as a shunt pump when needed. It is very clever and sadly most plumbers don't have much of an idea of how and what it does. Lots of ignorance surrounds it.
Because plate heat exchangers are so efficient as they transfer 90% plus of thermal heat, the boiler can be set to around 70 to 75C instead of the old 80C using DHW copper coils
The operation of the store, being heated directly by the boiler, with no coil, uses thermal layer storage. This means it is heated top down. This is very efficient. The hot water at the top is then pumped out to a highly efficient DHW plate heat exchanger. The store only needs to be 10% heated and useful hot water is extracted. With the old copper coils nearly the whole store needed to be heated to get hot water. There is a massive difference between the plate heat X and coil heat X models.
Thermal layer storage also gives very cool water at the bottom of the cylinder enhancing condensing operation. The boilers will run in ciondesning mode until 80% plus of the store is heated. The DHW pump send cold water directly into the botom of the store.
If the store was heated via a boiler coil it is heated bottom up, which again is less efficient than being heated using thermal layer storage.
Directed heated via a boiler and using a DHW plate heat X is the best combination. Then the store acts a CH buffer evening out CH demand. The smart electronics of the Boilermate then makes it sing.
They had a reputation for sludge, although I have never come across it, because many were poorly fitted. A great product. Well thought out.