An in-process component is implemented as a DLL CALLED ACTIVEX DLL, and runs in the same process space as its client app, enabling the most efficient communication between client and component. Each client app that uses the component starts a new instance of it.

An out of process component is implemented as an EXE called ActiveX EXE, and unlike a dll, runs in its own process space. As a result, exe’s are slower then dll’s because communications between client and component must be MARSHALLED across process BOUNDARIES. A single instance of an out of process component can service many clients.

An in-process component is implemented as a DLL called ActiveX DLL, and runs in the same process space as its client app, enabling the most efficient communication between client and component. Each client app that uses the component starts a new instance of it.

An out of process component is implemented as an EXE called ActiveX EXE, and unlike a dll, runs in its own process space. As a result, exe’s are slower then dll’s because communications between client and component must be marshalled across process boundaries. A single instance of an out of process component can service many clients.