[Passage Analysis]
P1: Few historians studied Russia and US’s serfdom and slavery's comparability / Kolchin done it.
P2: While tiny number of Russians owned serf, quarter owned slaves / Mostly more than hundreds serf in Russian serfdom while only 2 percent owned more than hundreds of slaves / Intermediaries in Russia while not in US.
P3: Resistance / Russia had four big ones because of large number of serfs as well as small ones called 'volnenie' / US rarely had noticeable revolts like the ones in Russia. / Reasons for each speculated.
Overall: There were number of conspicuous differences between US and Russia’s slavery and serfdom, few historians analyzed, which explains the resistance.