Si also uses a LOT of simple, rigid cause and effect terms while Ni uses blanket ones:
NTJ vs STJ example
Si: Shooting a gun at someone in the head will kill them. Shooting them in the stomach will cause a slow, painful death if not treated. Shooting them in the foot will not kill them, but it will give them a limp.
Ni: Shooting a gun at someone will hit them with a lot of force in a small area, if the force hits them in the right spot, they will die. If I do it right, they wont die instantly, but slowly.
NFJ vs SFJ example
Si: Doing things for people makes them happy, which is good. It makes me feel good for others to feel good. I like when people rely on me, then I can do more good things for them.
Ni: Doing things for other people can make them happy, but doing it too much may make them rely on me. I'll be nice to a person if I think it will do them good, but who knows? If I'm not quite sure I probably won't bother.
Hmm. I must be an ISJ, then because I'm the only one in my family who can ever remember where we parked. However, why I store things where I store them usually turns out to be "because it was convenient at the time," but I can still always find them...
Everyone has a balance between S and N and introversion and extroversion. Simple as that
And I do the same with storage: It may LOOK disorganize, but in my mind its all perfectly where I left them so it IS organized.