NRAM has a density, at least in theory, similar to that of DRAM. DRAM consists of a number of capacitors, which are essentially two small metal plates with a thin insulator between them. NRAM is similar, with the terminals and electrodes being roughly the same size as the plates in a DRAM, the nanotubes between them being so much smaller they add nothing to the overall size.
However it seems there is a minimum size at which a DRAM can be built, below which there is simply not enough charge being stored to be able to effectively read it. NRAM appears to be limited only by the current state of the art in lithography. This means that NRAM may be able to become much denser than DRAM, meaning that it will also be less expensive, if it becomes possible to control the locations ofcarbon nanotubes at the scale the semiconductor industry can control the placement of devices on silicon.