Ok, so a "Quest" is what we call a Sunfall event: "Hey, I'm running a Quest!" or "Hey, are you coming Questing this weekend?". It's epic and fun, so it fits!
There are three main types:
These are typically 4-5 hour events that run in a city park, or other cool facility. They are typically outdoors, but that's by no means a necessity. All the players play at the same time, and play flows back and forth from area to area as characters pursue the plot or subplots!
These are typically also 4-5 hour events, but run and set in a tavern or hall setting. They tend to be lighter on major combat encounters and huge set pieces, and are often focused on a central in-game event. All the players play at the same time, and play flows back and forth from area to area as characters pursue the plot or subplots!
These are the big 'uns... usually spanning one evening and the following day, and typically ending in an out of character feast. All the players play at the same time, and play flows back and forth from area to area as characters pursue the plot or subplots! Usually these are hosted at a campground, Scout camp, or other rural property.
There are also a few rarer types of quests:
These are small dungeon crawl events, where typically players assemble a team and then proceed through the dungeon one team at a time. The organizers reset the traps and sets between groups.
These are small events to encourage new players, so they are often run at Conventions or similar events or even in schools. They tend to be designed to being focus on every aspect of the game and rules, a little bit!