In this case, 'elements' seems to refer to the number of sections of the set that are independent -- the stages of the rocket, the lander, the astronauts, etc.

In this case, 'elements' seems to refer to the number of sections of the set that are independent -- the stages of the rocket, the lander, the astronauts, etc. Also, they specifically refer to the "LEGO Ideas" collection; the Taj Mahal was part of the "LEGO Sculptures" collection. (There have been many other sets from other collections with more pieces than this.)