I used to work in a former soviet republic, Kazahkstan specifically. It was amazing to me that there were two very separate spots to be filled in on any form, citizenship and nationality. As and American, I always figured the two were pretty much the same, but not there. The former communist masters used "divide and conquer" to help keep the masses under control. Part of their strategy, especially under Stalin, was to move troublemakers from their home country to a totally different soviet republic and cut them off from home. In the small part of Kazahkstan I was in there were Kazahks, Uzbeks, Georgians, Ukranians, Czechs, Germans, Koreans, Tartars, and even Russians. No one nationality, not even Kazahks, were in a majority. The Soviet masters emphasized the nationality so the troublemakers that were moved were pretty much isolated for a generation or two from the local population so they could not stir up trouble in their new home. It also helped dilute the power of the indigenous population so the Russians that lived there could remain masters. These prejudices remain, especially with the older people. It surprised me how scared most people were of anyone of Tartar nationality, for instance. I think that policy has a lot to do with the trouble that the Uzbeks are having in Kyrgyzstan that was recently in the news as well as many other problems in that part of the world.
I know Im rambling, but this section is called random ramblings so I guess Ill go a little further. I dont know where you are working and it is very possible the people you are working with are actually Russian citizens of different nationalities. When I was working in Kazahkstan, many Americans (Europeans too) would immediate talk about me working in Russia. I was not in Russia. Russia is a separate country. The former soviet republics got their independence around 1991 and do not consider themselves Russian at all. That was equivalent to telling someone that is working in Canada that they are working in the US.
I guess one more story. When Kazahkstan got its independence, they faced a big decision. What was going to be the official religion of the country. No one religion had a majority, but the two leading candidates were Eastern Orthodox and Islam. Eastern Orthodox was tied too closely with Russia, so of course they chose Islam. The reason they had to choose a national religion? So they would know which holidays to make official.
Anyway, Im sure Ive bored enough people enough. Have a nice day.