My dear nakamura12 -- the man which gave me my second merit on this forum (and, as I said with other occasions, I'll never forget that -- it's just a way of speaking: most users, when they refer to "DT users" refer mostly to "DT1 users". DT2 users also influence Trust scores by their feedbacks, this is true, but usually when saying "DT users" it's implied that the reference is about DT1 users. It's just semantics, if you want.

The difference between the two categories is that for DT2 you only need to be on the Trust list of a DT1, while for being DT1 more criteria need to be satisfied in order to be eligible -- and not even by then you are a DT1 for sure, as the monthly reshuffles can keep you off DT1, even if you meet the criteria.