The monarchy lasted for hundreds of years in Russia and Stalin's rule was only thirty, there were many different Tsars, cruel ones, enlightened ones, clever ones, pious ones, stupid ones and despotic ones. So I'll compare Stalin to the monarchies of the last two Tsars, Alexander III and Nicholas II.
Similarities:
Life was cheap - the Tsar and Stalin thought nothing of having political rivals exiled, Stalin was crueler and had more executed.
The State played the biggest role in industrialisation. Under Alexander and Nicholas the country was beginning to industrialise, but the industrialisation was for iron and steel for railways and guns, textiles for uniforms and coal to fire the furnaces of industry.
For the peasants movement was limited, there was an internal passport system, so people could not simply move around if they fancied it.
Both had enormous secret police organisation.
Differences:
The Monarchy was bound up with the Orthodox church; Stalin, despite training for the priesthood, was an atheist and hostile to the church.
The Monarchy was fabulously wealthy, as were most of the aristocracy; Stalin lived a modest life, he had no palaces, no court jeweller and no crown jewels.
The poor were exceptionally poor under the Tsars, the peasants were mostly subsistence farmers not wealthy farmers.
Education under the Tsars was very poor - just 5% were literate; Education was very good under Stalin 95% literacy.
Most people lived in the countryside under the Tsars' they were urban dwellers under Stalin.
Only the aristocracy could have political influence under the Tsars; only party members could have political influence under Stalin.
Women could not be educated, begin divorce proceedings, stand for political office, have an abortion or had many career opportunities; they could do all these things under Stalin
Both were cruel despotisms, Stalin was crueller, but, for those who did not fall foul of the regime, life was better in many ways under Stalin.
