The term Frater Lucis means Brother of Light and Fratres Lucis means of Brothers or Brotherhood of Light. Illuminatti means Iluminated.

Nothing in the terms "Fratres Lucis" or "Illuminatti" just as nothing in the words "Rose + Cross" or "Freemasonry" means superiority in any way, for all of these paths leads to the same goal, even with different forms and methods. 

But over time there have been many orders and fraternities that have made use these words interchangeably, with different meanings.What we mean by this? Each Order or Fraternity will have its own answer. Precisely because each has a different method with its own kind of work and must be respected for this same reason. Be that Martinist, Thelema, Freemasonry, not Illuminati, Rosa + Cruz or whatever name they use. Each has its own method whose goals are the same.

But they can only be true in the sense that they are really an emanation of the invisible Church which tells us about our

Master Eckarthausen.
KARL von ECKARTSHAUSEN wrote in his first letter of "A Cloud over the Sanctuary":
"The highest purpose of religion is the most intimate union between Man and God. And this union here and now is already possible but by the opening of our inner and spiritual sensorium that makes our heart more open and more succeptible to reach God."
"These are great mysteries that philosophy doesn't even suspects and whose words can not be found among the wise from schools."
"However, a higher school have always existed to which was entrusted the whole of all science, and this school was the Inner and Lord's Luminous Community and Company of Ellected Man and Women, that has spread over the world without interruption since the first day of creation until the present time".
"It is true that although its members are scattered around the world, they have always been united by a spirit and a truth and never had more than a knowledge, a source of truth, one Lord, a doctor and a teacher. A doctor and a master , which is substantially the universal fullness of God and that He started only in the high mysteries of nature and the spiritual world. "
This Community of Light was named thorugh all times the Invisible and Inner Church, or the Oldest Community of which we will discuss further in the next letter ...".