Basically, Structural Modeling is the set of interconnected components. That is, it describes the structure . The visible components are instantiated in the declarative part of the architecture body while the declared components are instantiated with their respective interface ports in the statement part of the architecture body. Structural Modeling doesn’t say anything about functionality.
The component instantiation statements are concurrent in nature. Thus, the order of these statements is not important.
Dataflow Modeling on the other side, includes declaration of a target signal using logical events occurring on the particular signal. Dataflow Modeling is primarily expressed using signal assignment statements. The structure of the entity in this can be easily deduced. In this case, a target signal is expressed using logical operations. The signal assignment statements are concurrent in nature, again the order in architecture body doesn’t matter.
Whereas, Behavioral Modeling deals with the functionality of an entity. Here, the set of statements are executed sequentially in a specified order, mainly specified within a process statement. The process statement is itself a concurrent statement but inside it lies a set of statements which are all sequential in nature.
Id:181-35-303