Many answers could be given to such a question. In my mind, Poland suffers from "Small Nation Status," which is a condition that sees the specific nation constantly overrun by its neighbors and not able to fully establish its own identity. Trace its history in the 20th century as an example. Initially, Poland was taken over by the Central Powers in WWI, then Germany took it over in WWII, and finally Russia took it over after the Second World War. Russia's size and population, as well as its wealth of natural resources, and its inability to be conquered because of its massive condition helped to develop its status as a great power that would come at the hands of the nations such as Poland.
I agree with everything the first answer says. But I would like to add a point about the geography of the two countries. As far as geography goes, it is not just the size of Russia that matters, but also its location and its neighbors. Poland had Russia on one side of it and Germany on the other. Both of these were dangerous neighbors. By contrast, Russia did not really have any dangerous neighbors (with the exception of Germany) for most of its existence. Because of this, Russia could expand to the east and south fairly easily and did not have to fear any sort of invasion from those directions.
The simple answer to this question is resources and territory. Russia covers nearly one sixth the land surface of the Earth, and is rich with minerals, oil and other resources necessary for expansion and empire.
Russia is also geographically blessed in that its vast territories are unconquerable without the use of nuclear weapons. Ask Napoleon and Hitler how their efforts at invading Russia turned out.
Poland, on the other hand, is sandwiched in between Germany and Russia, and has served as a natural invasion route for Mongols, Huns, Russians, Nazi Germany and later the Soviets, among others. Therefore its very existence as a nation was frequently threatened as it was swallowed by armies and empires from each direction. It also has far fewer resources, and a much smaller population than its powerful eastern neighbor.
One could also argue that Russia emerged as a world power due to leadership on the part of 19th century Czars, whereas Poland has suffered from centuries of misrule and conquest.