https://en.m.wikipedia.org/wiki/Marshalling_(computer_scienc...
> Marshalling can be somewhat similar or synonymous to serialization. Marshalling is describing an intent or process to transfer some object from a client to server, intent is to have the same object that is present in one running program, to be present in another running program, i.e. object on a client to be transferred to and present on the server. Serialization does not necessarily have this intent since it is only concerned about transforming data into a, for example, stream of bytes. One could say that marshalling might be done in some other way from serialization, but some form of serialization is usually used.[1]
I'm most familiar with the term "marshaling" from COM, where it is quite distinct from serialization.
While others have already given examples re "marshalling" I'll go ahead and add one to the pile: Ruby also uses this term[1]. However, in my ~10 years of working with Rub daily, I have never Marshalled anything, nor have I known anyone who has. On the contrary, the few pythonists I talk to on the regular seem to be pickling all the time.
...but I seem to be maybe getting off track here.
By the way, pickling is great for transmitting data at runtime between processes that you own, because it can marshal almost any Python object and it's very fast. But it's bad at storing data (on disk or in a database) because it can execute arbitrary code and the format of the objects can change between package releases. That's quite different from marshaling as JSON, which is a very stable format supporting a deliberately restricted set of types.