How is a free rig different than a Carolina rig with a really short leader?
I don't think I understand what a free rig is, how to fish it, or what it's supposed to be doing under the water. I'm not even sure how to know I have a bite.

Great question! Truthfully, they are very similar. A free rig - the weight will generally not have as much distance from your hook when you are dragging. A carolina rig you can have a super long distance between your weight and your bait. The way I put it, I use the free rig for shallow cover and vegetation - carolina rig for deeper water, dragging points, rocks, etc.

Here are two good seminars to watch: https://www.bassuniversity.com/videos/fundamentals-of-the-free-rig-mike-iaconelli

https://www.bassuniversity.com/videos/carolina-rig-bass-fishing-greg-dipalma

Hope this helps!