For instance, Si: external dynamics of fields vs Ti: external statics of fields. It's cool in the ways they're similar, and it's just the statics/dynamics that is different, the way Se and Te are similar/different. And what's also interesting is how all 4 of them are external (tangible.)
So, as I was driving I was thinking about how as you change position in space your relationship to everything around you also changes, and how that dynamicism relates to the dynamic nature of Si vs the static one of Ti. So, in my above example of my sister using Si, you have her sense of direction. As she moves her relationship is changing to everything else and this change is always being tracked, and she can easily see how traveling in this direction or that will lead to other destinations as she knows where they are in relation to her pretty much all the time. Or you have when she's shooting, she's controlling her breathing and her movement and recognizing how these things are constantly impacting the position of the barrel and thus the timing of the shot.
But Ti is the static aspect and it's all the static connections between things, which just changing dynamic/static can completely shift things. So, you're still seeing how things relate to one another, but not how they're shifting and changing. So, it's like you're standing in place, and you see how far this thing or that is from you and from each other, the distance between each thing, etc. There are more qualities of the relationship being taken into account, but without the movement. It becomes information about how things tangibly relate to one another, and not where they're going. Pure spatial relationships can be Ti then, but the constant awareness of oneself within space and how you relate to the shifting nature of it goes with Si. It's interesting. Both are tangible relationships between things, but from different viewpoints: static/dynamic.
And then the relationship of both of these to the other tangible aspects: Se and Te. These don't look at relationships between things, but rather the things themselves. Se is static and all of those tangible characteristics, like size, shape, color, texture, but then Te is dynamic and so you have instead what those things are doing.
And Te and Si have just the difference between them of the objects, vs the relationship between those objects. It makes it an interesting thing to think about when you start adding each together, as in Te + Si, or Se + Ti, and the statics/dynamics then of types themselves. I find it interesting, but am spoiler-tagging it bc idk how much this applies to your question, or if anyone else will find it interesting.