You kind of answered your own question. Panels could be fan made as well, just depends if your showcasing something or dropping some knowledge on a certain show, game, etc...
That's why they have a brief description on the panel/fan event in the fanime program guide. It's there for you to decide if it's worth going or skipping it.
Not trying to speak for anyone, but I believe the question is "Fanime officially makes a distinction between two different types of events: Panels and Fan Events. What is the difference between these two official categories?" It's not a question of the events in the category called "Panels" being fan-run or not.
I have the same question -- Fan Events aren't given much of a description on the website as to what counts in that category vs. what counts as a panel, especially in cases where there seems to be overlap. As far as I can tell, Fan Events seems to be a catch-all category for scheduled events that don't fit neatly into being termed a "panel," but otherwise, it's not clear where the distinction is.
I suppose it doesn't matter terribly much, since as long as the events take place, it doesn't matter what the con terms them, but I'm interested to know the answer.
(Also, off-topic but since it's on my mind after trying to navigate the website to look at the panels schedule: the website is nearly impossible to navigate on a Microsoft Surface. Nothing responds to a finger touch, only a stylus touch, and that's not how I usually browse. Not sure who to bring up this issue to, or if it's so niche it might be a non-issue for the majority of attendees. Not sure how the website responds to toher touchscreen devices.)