The states of East and West Africa that are discussed in this chapter of your text were very similar in many ways. For example, both of these types of states gained their economic strength from trade. Both were dominated by Bantu peoples. Both were, eventually, dominated by Muslims as traders brought the ideas of Islam to these states. These factors made the states similar in important ways.
The differences between the states were mainly in their details. The states of West Africa prospered because they were part of a trading network that connected them to North Africa by land routes. By contrast, the states of East Africa were connected to a maritime trading network in the Indian Ocean. The East African states were made up of people who spoke Swahili. The West African states were also made up of people speaking Bantu languages, but these were different Bantu languages. The most important difference, though,has to do with the size of the states. The West African states were relatively large states. For the most part, this was not true of the East African states. With the exception of Zimbabwe (which is more of an interior state anyway), the East African states were city-states. This came about because of the importance of port cities in the maritime trade of East Africa.
Thus, while there were many similarities between the states of these two regions, there were also some important differences.