[Boost-users] [Boost.Asio] defer, dispatch and post differences?

The free functions *defer*, *dispatch* and *post* all have the exact same set of overloads and description in the library's reference (version 1.66.0). I also couldn't find anything on the subject in the *Overview* section of the library's documentation. Is the differences between them clearly described somewhere else, that I've missed, or could someone explain it? Thank you, Daniel