Although both look very similar, there is an important difference between the Composite Model Frame and the DSL model type (block definition). The Composite Model Frame consists of slots and signals connecting them. In the slots only the inputs and outputs are defined, furthermore the type of element can be predefined, this means you can specify here which type of element shall fit into the slot (e.g. ElmDsl* or ElmSym*). The Composite Model Frame serves as the basis for a composite model.

The DSL model type doesn’t have any slots, but it can be built using the graphical interface (blocks) or by writing equations. The input/output parameters of the DSL model type have to match those defined in the associated slot in the Composite Model Frame. The DSL model type serves as the basis for a DSL Model (ElmDsl), which can be inserted into the slots of a Composite Model. For more information about these topics, refer to the User Manual and Dynamic Modelling (DSL) Tutorial.