GVFS

userspace virtual filesystem - server
gvfs is a userspace virtual filesystem where mount runs as a separate
processes which you talk to via dbus. It also contains a gio module that
seamlessly adds gvfs support to all applications using the gio API. It also
supports exposing the gvfs mounts to non-gio applications using fuse.

GIO

GIO is the input, output and streaming API of glib.
It on the one hand provides a set of various streaming
classes to access data from different sources in a convenient way
and on the other hand it provides a high level file system
abstraction to access file and directories not only local but also
on the network. For the latter you need to install gvfs.