Okay, I have an idea.
Let's say I define a cup as something that stores and holds liquid. When the cup has liquid in it, we could say it loses the ability to hold other liquids, until its poured out. So let's say your self is the cup and the liquid represents Jung's psychological functions that can take hold in your cup. Now each cup is going to have a different shape or form that's unique to the individual and will effect how it holds liquids. But as you get liquid in your cup, your psyche becomes filled with a particular way of being with the world (psychological functions) and it becomes harder to change that, unless something traumatic happens that spills all the liquid from the cup. And the more you fill your cup with the same liquid, the more it creates a pull on your psyche to orientate yourself with the world in a certain way. It's a conceptual understanding that can apply to an infinite amount of possible cups and has the potential to help each cup better understand their orientation and its inherent nature. That's how Jung's types are. You learn the concept of a cup as best you can and see how different cups are filled, hopefully to gain some insight on yourself and other people, especially given that everyone is different to some degree. So how does this differ from MBTI and Socionics?
With Socionics it says to be a certain cup you need to have certain characteristics. You gotta be round and tall or have a lid that closes or be heat-able in the microwave or fill your cup with certain liquids and in certain amounts. And other cups have to have certain characteristics as well. The Jungian conceptual understanding still applies, but concrete characteristics are delineated from them, which may or may not be accurate or always true, but they are described nonetheless. This follows a Behaviorist approach and can be completely inaccurate at times.
With MBTI it says you need to have certain behaviors. Do you generally think a certain way or act a certain way or approach your problems in one typical manner or another? Then you are a stereotypical cup that is distinctly different from other stereotypical cups. The Jungian conceptual understanding also still applies, but now we let people decide what they are based on what they believe their thoughts and actions are comprised of rather than encourage people to investigate the nature of their being. This seems to blend Cognitivism and Behaviorism, but fails to let people investigate themselves as it blurs the Jungian concepts into stereotypes that may or may not be accurate.
So anyway with that in mind, they are different lenses of the same thing. Yes, technically they see different things because of how they focus, but what they are staring at is still conceptually the same.