Just curious, why are they called fake legos if they are practically same thing, is it just because of the absence of official brand name?
It's deference to the fact that Lego has consistently maintained quality for several decades (at the cost of affordability). It has always been a premium toy compared to others, whether today or thirty years ago.
This toy brand survived because it promoted both creativity and encouraged young children to make something structural and definitive with their hands (unlike clay) — this kind of "toy" was usually reserved for teenagers and adults through model building and other hobbies.
It was only (relatively) recently that Lego began licensing themes from popular culture, starting with the prequel trilogy in 1999. Before that, they had their own "universes" for various lines/themes that continue today.
There's a sense of accomplishment associated with building even the smallest set that's difficult to explain, the emotions it evokes are a sea of intangibility. I highly suggest you get a set and try it out. One of the first things I do when I move to a new place is to buy an inexpensive set (under 1000), build it, and then rebuild it differently over time. It gives me a calming feeling of satisfaction and pride during the transition where I would lack confidence in every other aspect of life while adjusting to new coworkers, new neighbourhoods, etc.
"Fake" legos bring the cost of entry down, especially for those who aren't collectors and are looking primarily for an easy outlet for their creativity. The term "fake" isn't meant to be dismissive (as someone might infer). it just differentiates them from the original.