For example, political theory deals with the abstract aspects of politics, and similarly, there is theoretical (abstract) physics. Why are they called abstract or theoretical? Is something that we study not supposed to be a reflection or a representation of the real or of what happens in practice?
Ok, let me try to clarify the difference. As an English writer, I hope it helps. But you could also translate the terms into your own language and seek sources for those terms.
In theoretical work we form a hypothesis about something unknown (or only partly known) and then seek evidence as to whether the hypothesis is true or not. The subject of the "theory" might not even exist. In theoretical work you are exploring the unknown. You are attempting to add "detail" from the real world - evidence to support the hypothesis or not.
Abstraction, on the other hand, is a process of removing details from a complex topic to try to come to the essence of some question. For example, democracy is an abstract concept that exists in the world in many forms, some of them very messy. The abstract concept of democracy removes much of the detail to arrive at some core "essence" or abstraction of the idea. So, the US and the UK are both democracies, but have a very different governmental structure. But, there is not really such a thing as a "pure democracy" conforming to the idea without any of those messy details. Abstraction lets us work with very complex systems in a simpler form.
Language, actually, is a form of abstraction. Many of the things we speak of would be impossibly difficult to discuss without the simplification of removing details thought to be unnecessary to the essence. If you want to discuss me for example, then, for most purposes, you don't need to know my height or hair color. The me you discuss is an abstraction.
It would be possible to work in the political arena in a theoretical manner. One could devise a theory of government not represented in the world and then seek evidence as to what the effect would be. Science Fiction does a lot of that sort of thing.
On the other hand, one can do physics as a form of abstraction, looking at what exists in the world and trying to "abstract" what is making it behave like it does. The orbiting of the Earth around the Sun was explored in this way. See Heliocentrism. At the time of those explorations, there was a Theory that the Earth was the universe (or, more properly, a religious dogma). But in the end, that theory proved to have little evidence.
Note that the "elliptical" path of the Earth around the Sun is itself an abstraction. The Earth is deflected slightly from the ideal elliptical path due to various forces, such as passing asteroids.
And, sometimes a field has to go back and forth between theory and abstraction, when a theory needs to be revised due to contrary evidence, leading the practitioners to try to devise new abstractions that might be better representations other aspects of the data not originally considered.
So, you can't say that it is all abstraction or all theory. You need to consider the process by which researchers in a field actually work.
Finally, theory, itself, is an abstraction.