A question that often goes along with discussion of a degree system is about titles.
Going to a convention one can barely turn around without tripping over a Lord High this or Supreme Lady that.
Anyone who spends enough time seriously studying the occult will accrue titles of one sort or another; anyone who has actually earned the titles tend to be loath to use them outside of specific formal circumstances.
Within Path of Light we call each other Brother or Sister; a third degree may affectionately, or on occasion chidingly, refer to one of their students as Little Brother or Little Sister. A student would never refer to their teacher as Big Brother or Big Sister.
At the third degree one takes on the title of Lord or Lady within Path of Light tradition, this is an ecclesiastically bestowed title and carries the same weight as Reverend or Pastor however it is rarely used outside of specific formal contexts. When performing pastoral or ministerial duties such as at a hospital or a prison we use the more simply recognised "Reverend".