I often listen from people saying der baume, which means the tree (Family tree / or computational tree structure), which I usually mix with plant trees, or sometimes das fenster which I mix with room windows however they also call computer windows as fenster. I would like to know, do they have all translation of computational words in German? If no then is there any rule to distinguish which computational word goes in English and which should be in German?
If I understand you correctly, your asking whether all computer-related technical terms get translated into German, and if not, how it's decided whether a term gets translated or not.
In my experience, it depends on a lot of factors. One of those factors is familiarity. If the concept behind the technical term is around long enough and people come into contact with it regularily, they may tend to use the familiar German term for it instead of the foreign terminus technicus. Windows as parts of graphical user interfaces (GUIs) have been around for decades now, so people are often comfortable with calling them "Fenster".
On the other hand, I don't remember ever hearing something like "Großdaten" für "big data". The concept isn't around that long, and people typically don't get into contact with it on a daily basis (or at least they don't realize they do), so they tend to use the English term that came with the concept.
Another factor is comparibility. If the technical concept and the "real world" concept are comparable enough, people may also tend to the use familiar German term. To my knowledge, GUI windows were actually modelled after the idea of a hole in the wall. So the concepts are comparable enough to use the same term for both, in English as well as in German.
On the other hand, a "server" in a computer network is something significantly different from a "Diener" or "Kellner". The concepts aren't really comparable, so people tend to use the English term in German, as well.
There are other factors as well, for example marketing ("Our product doesn't have ordinary 'Fenster', we have spiffy 'windows'!") or just whether a fitting and handy German term exists (how would you translate "cache" into German without writing one or multiple sentences?).
So, as often with language, it depends :D