An inprocess is one which runs in the same process area as 
that of the client giving tha advantage of speed but the 
disadvantage of stability becoz if it crashes it takes the 
client application also with it.

Outprocess is one which works outside the clients memory 
thus giving stability to the client, but we have to 
compromise a bit on speed.

Inprocess is faster than outprocess.

An in-process component is implemented as a 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, 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.