never been on Nextdoor but probably similar. Perhaps purpose would be the main difference - Nextdoor is residential and problem orientated, whilst our idea (we actually had it to MVP) was more like foursquare meets old twitter - basically verified local recommendations, news, updates from folks who were actually local to the area, rather than transients who know little. Our attempt then the limit the transients to read only translates really well today to online trolls / bots etc