`io_context.stop()` vs `socket.close()`

To close a Tcp client, which one should be used, io_context.stop() or socket.close()? What aspects should be considered when making such a choice?

As far as I know, io_context is thread-safe whereas socket is not.

So, I can invoke io_context.stop() in any thread which may be different from the one that has called io_context.run(). But for socket.close(), I need to call io_context.post([=](){socket.stop()}) if socket object is called in a different thread(e.g. the said thread calls aiso::async_read(socket, ...)).