Hollywood = the major US filmmaking & distribution industry; big money, wide distribution in the US.
Indiewood = the "place" in the US where real independent and hollywood meet and give birth to Napoleon Dynamite type movies, also the "place" that produces low budget & "edgy" hollywood movies that receive relatively wide art house & beyond distribution. You should be able to catch a lot of indiewood movies at Landmark theaters, also smaller independent theaters that program Landmark type stuff & on IFC.
Festwood = the US independent film festival scene. it is possible for a real indie film to do very well in Festwood but have no impact in Indiewood or Hollywood - and some films don't need to make it to the H-wood or I-wood level or are better off without it. Sundance film festival & SXSW film festival are two of the bigger festwood events in America.
(perhaps festwood can also include film festivals world wide, not just US based ones, since festivals in other countries can have an effect on what films get programmed for festivals in the US, and this happens in the other direction too)
DIY = working outside all four above mentioned arenas & avenues of film production & distribution, a great & chosen place for some, a place that most US indie filmmakers must start at 'cause the other four arenas are progressively less accessible to "no"/"low" budget & "unknown" US indie filmmakers.
note: it is possible for one project or one filmmaker to be part of several of these arenas at the same time.
What do you think about this breakdown? Might it be useful in making sense of the gigantic planet wide practice of filmmaking & distribution, for US based indie filmmakers? Lemme know.