|General local cases|
The partitive indicates a part of something. Along with the accusative, the partitive also indicates the object of the action. Anyway, the main difference is that the accusative is used, when the action is directed at the whole object, and the partitive, when the action is directed only at a part of it. In English, this difference is sometimes expressed by omitting the article or by replacing it by the word some. The partitive suffix is -a/-ä/-ta/-tä in both the singular and in the plural.
The essive expresses the state of something. It often corresponds to the preposition as. The essive suffix is -na/-nä in both the singular and in the plural.
The translative expresses the result of a process of change. The English verb become includes the meaning of this case, for example. The translative suffix is -ksi in both the singular and in the plural.