In general, Emacs display elements (windows, frames, etc.) are not tied to any specific data or process. Buffers are not associated with windows, and multiple windows can be opened onto the same buffer, for example to see different parts of a long text side-by-side without scrolling, and multiple buffers can share the same text, for example to take advantage of different major modes in a mixed-language file. Similarly, Emacs instances are not associated with particular frames, and multiple frames can be opened displaying a single running Emacs process, e.g. a frame per screen in a multi-monitor setup, or a terminal frame connected via ssh from a remote system and a graphical frame displaying the same Emacs process via the local system's monitor, etc. Because of this separation of concerns, Emacs can display roughly similarly on any device more complex than a dumb terminal, including providing typical graphical WIMP elements on sufficiently featureful text terminals - though graphical frames are the preferred mode of display, providing a strict superset of the features of text terminal frames.
