When I read about it on Wikipedia, it seemed to me that these two are almost the same, but the same article says that they differ not only in the use of DSL.
Note that a "fluent interface" means more than just method cascading via chaining; it entails designing an interface that reads like a DSL, using other techniques like "nested functions and object scoping".
I can’t understand how they are related And in other articles I saw examples where fluent interface is just method chaining, not cascading
Fluid interface and cascading method, implemented through method chaining, are related concepts in the sense that they both involve chaining method calls together, but they serve different purposes and have distinct characteristics.
Method chaining is a general programming technique in which you chain method calls for convenience and readability. Cascading method is a specific use of method chaining in which you chain methods on the same object for a series of related operations.
Fluent interfaces, while they may involve method chaining, are about designing APIs that read like domain-specific languages and often include additional design considerations beyond method chaining, making them more expressive and DSL-like.
Therefore, while they share similarities, they are not the same, and a fluid interface can encompass much more than just cascading via chaining.