I have the same question! According to Wiktionary, Gemeinschaft means a group of people feeling connected together (the more abstract 'sense' of community), while Gemeinde means an organized, administrated group of people in an area (the more concrete 'organization' of community) I wonder if this is the correct understanding?
Ok, so without looking at the dictionary hint I translated 'The parish is new.', which is wrong according to duolingo.
It's just that I usually use 'Gemeinde' in the sense of 'parish' and 'Gemeinschaft' for 'community'. Is 'community' a synonym for 'parish'? Or am I complete wrong in this?