There is so much of a difference between fetishes and porn. People who have fetishes don't necessarily like porn, and people who watch/read porn don't necessarily have fetishes (other than for porn). Furthermore, not all porn is fetish porn.
A fetish is a sexual attraction to something that isn't necessarily normally considered sexual in nature (like feet or shoes or certain words)
Porn is printed or visual material containing descriptions of of display of genitalia or sexual activity.