American Religious Scene- Volume 38 - Episcopal Churches: Variety in one book

Unit 38 answers I've been to several Episcopal churches and their services all came from the Book of Common Prayer. However, even though they use the same book, the feel of the services was very different. Some of the services were very similar to a Lutheran service. But one service I want to seemed like I was in a Roman Catholic Church. With one book, why is there such variety?