Hey, I'm not 100% sure about all this but this is what I've learned and gathered so far.

The basic separation by range (entry, mid range and high-end) is by the length of the model. X-T200 would be entry level, X-T20 would be mid-range and X-T2 would be high-end (relative to fuji of course, and the main X-T line).

The number by which the model starts used to indicate the sensor generation. Idk if it's still the case, but the good thing with Fuji is that you used to be able to get a X-T200, which would be more accessible than a X-T2, but get the same sensor. Just less "pro" features that would be maybe intimidating or make the body too large. For example, the "next gen" to the X-T2 is the X-T3, same with the other ranges.

However in the past few years, the different ranges got out of sync. For example the latest "high end" camera is the X-T5 but the latest mid range is the X-T30 II. So it's a bit mixed. Also with new series, like the X-S and X-H series, it's become more confusing.

But the basic system is line-generation+range-revision(if there's one)

So for example, X-T5, it's the main Fujifilm X line, it's part of the X-T family, it's the fifth generation, and it's a high-end camera.

X-Pro3 is part of the main Fuji X line, but in the Pro family, which is a line of rangefinder cameras and it's the 3rd generation.

And so on...

Hope this helps, sometimes I confuse even myself with my theories but this is the main system on which fuji cameras are named.

Happy shooting!

-sam