In former times, Lego boxes used to feature a diagonal Legoland label in one corner. (See, for instance, the box of the Space Police I capital ship, set 6986.)
Later on (if I recall correctly, starting in 1992), the Legoland label disappeared, and instead a large SYSTEM label appeared on boxes (for instance, on the first Octan gas transit vehicle, set 6594](http://lego.wikia.com/wiki/6594_Gas_Transit)).
In both cases, my guess is that Legoland and System denote the "world of minifigs", as opposed to Duplo, Fabuland, or Technic - but I was never sure about this.
Looking at boxes nowadays, such a mark has completely disappeared, and boxes just indicate their theme (such as City, as on the prisoner transporter, set 60043).
Hence, my question is: What was the significance of these labels, was there any difference in scope between Legoland and SYSTEM, and why were they changed/discontinued?