Disassociating is something you do, whereas disfellowshipping is something they (the elders) do. Both have the same outcome as regards shunning, and the announcement to the congregation is the same.
Although disassociation is "self-inflicted" as it were, it can be forced upon you if your actions are interpreted as demonstrating that you no longer consider yourself one of Jehovah's Witnesses. An example would be joining the army, attending another church . I think regular attendence at a church after being spoken to would be considered defiance without actually becoming a member right ?
I think the reason certain things don't appear on the list is stated on page one...human rights issues
To be fully complete, you'd need to add the list of things that result in "disassociating oneself" (i.e., things that the WTS is afraid of being sued over, or afraid of losing prestige or influence over, so they didn't make the DF list):
-- Joining the military
-- Accepting a blood transfusion
-- Voting ~~~sir82