Com o lançamento do último set Bespin surgiu a dúvida do que poderia querer dizer "Master Builder Series". Penso que o significado era óbvio, mas aqui fica a clarificação da LEGO:
The Master Builder Series models are large playsets and beside being complex builds they are characterized by having many play features and functions, interior details as well as a range of minifigures. Ultimate Collectors series will remain highly detailed display models providing complex builds with a focus on authenticity and both Ultimate Collectors Series and Master Builder Series will continue as a way to highlight the unique characteristic of each style of model.