Although they do carry different emphases, they both refer to the spread of Russian culture, language and customs through the influence of Russian power and identity over other cultures and nations.
Russification is usually associated with the promotion and adoption of Russian attributes by non-Russian people.
Russianization usually refers to the active imposition of Russian language, culture and customs on non-Russian people or territories, involving the assimilation of non-Russians into Russian society.
We commonly describe the latter as Russification when, according to scholars, Russianization would be more applicable. It connotates political domination and control. Russification is the process of advancing cultural exchange and integration, while Russianization involves the forced assimilation and suppression of diversity.
(While scholars associate Russification with the Kremlin using moderate/soft power in wielding its influence, for this writer it covers all means of non-military Russian domination over others.)
If one were to add ‘Sovietization’ into the mix with the other two, then under Tsarist, Soviet and current Russian rule they all intend to ensure state control over a diverse population. Tsarist regimes, however, rarely attempted to actually assimilate the different ethno-cultures within the Russian Empire and destroy their national identity.
(Pikemalt saab lugeda Eesti Elu 8. detsembri 2023 paber- või digilehest eestielu.ca)