I think mass nationalization simply expands the knowledge of something through a nation, while cultural homogenization guarantees the acceptance of something as part of a culture.
If ideology of particular nationalism requires cultural homogeneity of population (i.e. nation), the two notions are strongly interrelated. As it was almost always the case, what matters is the direction of the relationship between the notions.
If cultural homogenization is seen as a prerequisite to mass nationalization, it implies the view of nation as formed by some kind of "preexisting objective criteria" (whether institutionally-driven or not). On the other hand, if mass nationalization is seen as a prerequisite to cultural homogenization, it implies the view of nation as forged by intentional effort of nation-building institutions.
In any case, mass nationalization provides "static" cultural community (whether preexisting or forged by institutional pressures) with "dynamic" political meaning and basis for mobilization behind nationalist principles. Therefore, "cultural homogenization" without "mass nationalization" creates no more than non-mobilized (unconscious) cultural group, while "mass nationalization" without "cultural homogenization" lacks common ground for mobilization potential (i.e. cohesive group).
Hopefully, we are talking about the processes of the past.