to bring it to point:

the Plus-member also receives all necessary help (in case of car breakdown, illness, injury, emergency cases...) in foreign countries. The normal ADAC-member just gets help within Germany.
So the Plus-membership is really helpful, if you are travelling a lot through the world.
Not included (as far as I know) is a classical health insurance for travellers, but for example the transortation back to Germany via medical aircraft is coverd for urgent cases.