In this video from February 2010, Ngakma Nor’dzin and Ngakpa ’ö-Dzin explain what it means to be an apprentice within the Aro gTér Lineage in terms of the rôles of Spiritual Friend and Vajra Master.
Apprenticeship is perhaps a little bit unusual there, in that it treads this line between the two. A Spiritual Friend is somebody who offers you general advice from the perspective of the teachings. They don’t teach so much with personality – the qualities of personality don’t come into that so much. It's not so individuated. The teaching stems from the teachings themselves. This is the Sutrayana approach.
For instance: a Sutric teacher may have hundreds and hundreds of students and this functions perfectly from the point of view of a Spiritual Friend because the teachings themselves are the relationship and you don’t individuate the teachings per person – you just teach in a general sense.
Now the Tantric teacher, the Vajra Master, teaches almost entirely individually. Even though they’re teaching general Tantric teachings, the relationship of the individual apprentice with those teachings will be quite personal and will be personally overseen by the Vajra Master. But as I say, apprenticeship is somewhere between those. There is the quality of personal relationship there but it’s not so extreme that one takes the presence, personality and life circumstances display of the Lama as one’s path. This happens later when one takes ordination.