help with phantom frames verses cruisers

HI. Does anyone know if there is anything unique with phantom frames verses other frames of the same years other than the locking forks? Reason being, I have a phantom fork, tank set and fenders with front light and would like to put together an accurate phantom, however, every frame on ebay for phantoms are big bucks verses lower cost for cruiser frames of the same years. They look the same to me. I cant imagine they would have a half dozen different frames for their cruisers of those years. Any help would be great. Thanks