You could however also argue that ideologies were the same pre 1917 and post 1917; this is because both the tsars and the communist government believed has leaders with a paternal role, all tsars had a paternalistic role in Russia and after 1917 a specific leader who showed as a paternalistic figure was Stalin. Stalin, similar to the tsars before 1917, through propaganda acted as a fatherly figure in Russia who the people of Russia looked up to.
Another way in which the October 1917 revolution changed government is in the difference in government structure, an example of this is that pre October 1917 the government, when ruled by the provisional government, consisted of two organs which was the Provisional government and Petrograd Soviet whereas after October 1917 it consisted of many organs and not just two. The government structure however, was also same in some ways; for example, before the October revolution the government worked with a hierarchy within it similar to after the October revolution. This continuity suggests that there was not complete change in nature of government.
You could also suggest that the function of government showed continuity rather than change after the 1917 October revolution. This is as in regard to reform both the tsars and the communist government acted on reform with a nod to democracy, the tsars with the introduction of the Duma and the communists with the introduction of the Supreme Soviet. The fact that both showed some form of democracy suggests that the October revolution had no effect on how the government functioned as there was obvious continuity in this sector.
In regard to repression it seems that there was change in the level of repression after the October revolution. Pre October 1917, it seemed that political control under the Provisional Government is relaxed and so radicals such as Lenin are allowed back in Russia showing little repression from the government over the Russian people, however through some of the Tsars such as Alexander III there is high level of repression over radical groups as well as censorship. This high level of repression is also shown by communist governments such as that under Stalin which used propaganda, censorship as form of repression to ensure that the people of Russia keep 'under the rules' which he puts forward as the paternal figure.
Overall I believe that the 1917 October revolution changed the nature and function of government in the period 1855-1964 but not completely. This is because evidence has shown that in regards to nature there is change in ideology between pre 1917 and post 1917 and continuity is little with the similarity of paternalistic figures. The function of the government also shows continuity as their reform within the government was very similar with both heading to democracy. However there is also evidence regarding function of the government which shows change as some of the tsar leaders showed very low levels of repression regarding their function whereas the communist government showed high levels of repression, therefore suggesting that the October revolution presented both change and continuity with the nature and function of government.