What is the difference between interactive fiction and a visual novel?

The main difference is emphasis: interactive fiction centers on text and player-driven choices, while a visual novel centers on illustrated scenes, character art, and a mostly-authored script with occasional choices. Visual novels lean heavily on visuals and sometimes voice, often presenting long stretches of story with just a few branch points, and they are strongly associated with anime-style art and Japanese origins. Interactive fiction tends to be more text-forward and can offer denser branching or parser input. The line blurs, though: a choice-based interactive story with art starts to look like a visual novel, and a visual novel with heavy branching looks like interactive fiction. Both are types of narrative game, just weighted differently between words and images. You can play text-forward examples on the play page.