Overtraining is more like an illness than "being sore". The symptoms are physical (you get sick, you're sore, you feel weak) but they're also psychological (you can't sleep, you are sad, your brain feels slow). You can train through being sore. Everyone gets sore. When training starts to negatively impact your quality of life, you are overtrained.

Realize that pushing your body to the limit does not make you learn faster. When I'm actually overtrained in Jiu-Jitsu, I don't get better, I get stupider. I do dumb things that I'd never do when I'm not. It's like being drunk sort of. Limits exist. Learn to vary intensities in training.

Not everyone can handle the same capacity for training. Genetics is a thing we don't really talk about in Jiu-Jitsu. Same with steroids. Same with life stress. Some people are naturally more athletic than others. Other people use drugs to recover faster. Others have the luxury of training full-time and having a low-stress life. Don't compare yourself to other people too much.

Take a few days off because no one is forcing you to train. If you're feeling worn down, the most important thing to do is to reduce intensity. Probably the worst part about Jiu-Jitsu's culture is the guilt trip about not training that people do. I've seen this nearly everywhere. If you're overtrained, just don't show up.

The knowledge lost by a few days off is chump change compared to the progress lost by an overtraining-induced injury. Most grappling-related injuries are overuse injuries. Most "accidents" happen to overtrained grapplers. Lesson in there about training in the sport.