New Jersey has two rather different regions. The south half of the state is on the low, flat-lying Atlantic coastal plain, and the north half is in the ancient folded Appalachian mountain chain. In fact they fit together very well, but the course of the Delaware River, which establishes the state border, cuts across and along the grain of the rocks giving the state its chunky shape.
Big difference. This map nails it for the most part. Entering the South, you come to the Pine Barrens, one huge wilderness where the mafia lay their dead to rest; to the north it's all refineries along I-95, though much of the north is forest, as well.