Wow, it seems I get to answer all sorts of niche questions today. It is like a second birthday. First of all, thank you for such an interesting, and complex, question. For the time period you are asking about, you are looking at two major things. First is the 19th century attempt to clean up inconsistencies in spelling and to put together some sort of standardization. This time period saw the introduction of Yakov Grot's textbooks that were the main source of seeing the spelling standardized along several principles. The 19th century also saw the introduction of Ё (yo) and the removal of the Cyrillic correspondence to the Greek upsilon. In summary, most of what you would see in differences from this time period to now would be standardized spelling, and a lot of extended specialized vocabulary. The next big change we see, if the Reforms of 1917. These were reforms that were put together by an Assembly of Orthographic Simplification. These reforms simplified inflections, dropped several confusing rules, and were intended to really close up and simplify the Russian language in an extremely standard, Soviet leadership approved way.

So far, I have mostly mentioned the orthographic changes. As for spoken, this is a bit harder to track. You see an overall shift away from archaic formal language to something more vernacular and (in the case of the 1917 Reforms) an attempt at something more modern seeming with the proper terms for appropriate political ideology, as well as a drop of certain politeness specific terms (basically forms of address in the like).

I hope this helps and feel free to ask for any further details if I did not answer your question in a satisfactory manner.