Complex sentence: The keep was designed as a private tower for Hamelin Plantagenet, rather than a grander or more complex castle designed to accommodate several different households, as seen at Orford Castle, for example.
Split into simpler sentences: The keep was designed as a private tower for Hamelin Plantagenet, rather than a grander residence. As a result, it was not designed to accommodate several different households and its layout was simpler than that seen at the keep of Orford Castle, for example.