Many working professionals use the terms with same flourish, without knowing that the two terms are distinctly different from each other. A director is essentially a person who directs the film; but a filmmaker is a person who not only directs the film, but is involved right from the conceptualization stage to writing, production, editing, even marketing & release and post-release sales of the film.
With films becoming increasingly tough to make, it is time to expand horizons; one needs to know the complete marketing & release process. A SWOT Analysis is very important in any stream of work you do, before you venture into it! It increases the probability of success!
Next time you make a film, try to be a real filmmaker and not just a director, you will find that you added an entire new dimension to your directorial.. err.. filmmaking skills!