The pre-game line ups:
Ukraine has 31% of the population of Russia, and 7.9% of the nominal GDP (12.6% at PPP). Note that these are comparisons of statistics from different sources, and not necessarily over the exact time periods, so the comparisons are a bit rough, but by all measures, Ukraine is a lot smaller, and much poorer.
From
http://www.bbc.com/news/world-europe-26421703, it appears that Ukraine has 15.4% of the armed forces of Russia, 44.4% of the tanks, 15.9% of the combat aircraft, and 9.9% of the combat ships. I believe the Ukrainian nuclear arsenal is 0% of the size of Russia's. These comparisons are numeric only, and don't really reflect whether there is any substantial difference in the qualify of the personnel, tanks, aircraft, or ships. It's also not clear that Ukraine would have a home field advantage, as Russia has military bases within the territory of Ukraine, and a substantial part of the Ukrainian population may well feel more affinity with Russia than with Ukraine. On the other hand, Russia is big, and a substantial part of its military resources are going to be spread around all over the place, whereas the Ukrainian forces are going to be more concentrated.
Still, I feel like Russian troops occupying Kiev is a more likely near-term outcome than Ukrainian troops occupying Moscow.