Overloading Vs Overtraining

I wanted to do a follow up post from my last one about overtraining....
There are two terms that are passed around gyms and the fitness world - 'Overloading' and 'Overtraining'. Some people do think they mean the same thing...which I can kind of see why, but they are very different.
As mentioned in my last post, overtraining is where you are training way too much without sufficient rest. I have made it crystal clear that this is BAD and you should never do it. Now, overloading is very different. Whether your a girl or a guy, if you want to gain muscle mass, you need to start overloading your muscles. This means putting your muscles under more 'strain' than they are used to. Have you ever seen a guy in the gym on the weights with facial expressions like they are constipated? well, that's because he is straining his muscles (which is actually tearing the muscles...) and this takes effort! This is what overloading is - putting more load onto the muscles, causing 'damage' which is then repaired to grow bigger and stronger. If you don't overload your muscles then you won't build more muscle. This will 'hit' your body hard, and it will require you to rest for at least 24 hours, if not more. I personally use the 'once every two days' method, where I workout once every two days (hence the name, duh!) and I find this works very well.
I hope this has helped clarify the difference between these two terms.