No, this isn't true at all. It is quite likely that Rome was more urbanized than Han China, but certainly not to a point where one could call them a dichotomous pair. Both were overwhelmingly demographically rural (probably something like 80-90% in Rome's case) but both had large, vibrant cities that directed a great deal of the economic activity. Neither were mercantile in that neither made it a primary objective of state policy to promote trade and commercial activity. Both had large civilian bureaucracies, but both also had large standing armies and could be aggressively expansionist.

I would be curious to know where you might have heard/read such an assertion comparing the two as such.