COM vs. Dispatch
The SolidWorks software exposes its API functionality through standard
COM objects. For OLE automation, the API is exposed using IDispatch.
COM implementations provide:
Your application direct access to the underlying
objects or arrays, and, subsequently, increased performance.
Slightly more functionality and also return
an HRESULT value for each API call.
The COM interface is recommended for all add-in DLL projects. For executable
(.exe) implementations, you can use the COM interface unless the method
or property passes an array. In this case, use the equivalent Dispatch
method that uses a VARIANT to encapsulate the array.