A group of people building gingerbread houses.
A group of schoolchildren are working on a gingerbread house neighborhood for class.
A group of people is not necessarily referring to schoolchildren. Just because multiple houses are being built doesn't mean that the houses are intended to be set up as a neighborhood.
Just because a group of children are working on gingerbread houses , does it mean that they are doing it for class.
People and houses don't imply schoolchildren and neighborhood.