I think they wanted to separate out four different concepts in the territory, needed a name for each one, and so picked four almost-synonyms for the labels on t

I think they wanted to separate out four different concepts in the territory, needed a name for each one, and so picked four almost-synonyms for the labels on the map. We can read "tutorial" in their system as a technical term rather than its everyday meaning, just as "depression" has a particular meaning to a psychologist that might not match everyday use. I guess that's still better than labelling them Type I-IV tutorials.