This question is not Russian language-related strictly speaking, but I think it's useful for a lot of people using the language. I wonder if it is possible to use the ruscorpora.ru website to build the comparative word usage frequency distribution by year for two (or more) words. I have found the user manual, but couldn't find the answer there.
If you are looking for juxtaposition-ed plots, you can do this:
You can start by clicking "графики" on the home page of ruscorpora.