I understand it all...I think xdNot a problem. ^_^ Actually, a lunge can be preformed with either one or two hands, but I generally teach the two-handed variant.
Stabs are quick motions that can be fatal, or used to break up an opponents combo, while a stab is generally just used as an attack, either to force back an opponent or hit one not in immediate range. It's not a great opening-mid combo move, so as long as your still a beginner, stick to it as a finisher. As people improve, you become more able to use it at your whim, as you can take care of openings you create.
Lunges have a lot of power behind them, and much greater range.
Once you get some practice in, you'll be able to get around the weakness of lunges by transferring your momentum, but that's for later.
You must be registered for see links
I find that this lady explains and demonstrates it far better than I could.
Please watch the video, and then preform a lunge, only, making adjustments to accommodate two hands.
*I quickly take out my Katana and I hold it with both my hands so that the point is poiting down but also I am keeping my sword at right. I then start rushing towards the dummie as fast as I can and as I reach short range (or the position to where the lunge would be possible), I but my front leg, which in this case is my right one, straight forward at the dummie while I move my whole body forward. Only my back leg, which in this case is my left leg, is straightnes out. As I perform all those movements, at the same time I draw the katana with my hands so now, it won't be at right but straight forward and as I do that, with a very fast and slight movement I straight my hands, putting the katana forward with great speed, lunging in the dummie's heart and then quickly draw back the katana.*
Don't know how I did here. xd