New Jersey and Georgia just have more landuse mapped at the moment.
This data seems to come from a Land Use and Land Cover (LULC) import, for example the data for New Jersey has *source=NJ2002LULC* (see [way 250286927][1]) and seems to be made available by the New Jersey Department of Environmental Protection (NJDEP). Likewise, some of the data for Georgia has *source=USGS-LULC* (see[way 31388469][2]) and seems to originate from the USGS Land Cover Institute (LCI).
If you want to improve the current situation then just [start mapping][3] :)
[1]: http://www.openstreetmap.org/way/250286927
[2]: http://www.openstreetmap.org/way/31388469http://www.openstreetmap.org/way/31388469
[3]: http://learnosm.org/en/beginner/start-osm/#beginning-osm-create-an-openstreetmap-account