My mother has Lithuanian ancestors, and they all were listed as coming from Russia in the 1910 census. As aghadowey mentioned above, the political issues can impact the country's name. It's also possible that the information came from someone who didn't know for sure or there were language/accent issues between the informant and the census taker.
Having the year of immigration vary from census to census is pretty common. People forget, or the informant didn't know for sure. You might also want to keep in mind the possibility that they went home for a visit and came back again.