No they are individual discs of a MUCH smaller version of the game than prologue. A genuine demo rather than an almost full-game like prologue (i say that due to its size compared with other racing games not compared to other gt games).
You are supposed to be able to get these discs from the respective dealers (did you actually ask?).
I don't know the tracks on the toyota one, but i do know it is basically in the trials roadster car (the weird open racer thing)
As for the bmw demo, it has the 120i and 120d cars in it and uses the nurburgring nordschleife, costa di amalfi and new york city tracks.