They're not a natural pair. In fact, it's hard to imagine a greater contrast. I haven't had time to think in detail about these games but I want to introduce them and compare.
Polaris is about somewhat elfin knights at the north pole fighting the demons that are inevitably going to destroy their kingdom. The narration duties are split up unusually. Four people play the game. For a scene about your character, the person sitting across from you creates adversity and the people to your left and right play the roles of the two types of NPCs (those you have an emotional relationship with and those who are related to you mainly by your role in society). All the main characters are doomed. Game play is highly ritualised. For example conflicts are resolved using specific phrases to let the others know what you are doing. The expectations for each player at each stage of the game are well-defined and the setting is extremely cool. The art and design of the book feed into the feel as well. My main problem at the moment is that there are five of us in my gaming group, so we can't really play the game (there are suggestions for playing with three or five players, but I feel like they would be sub-optimal). Overall, looks great.
Warhammer Fantasy Roleplay is about various adventurers having adventures. It's the second edition but stays true to the style of the first edition back in the 1980s. The career system is still there and just as cool as I remember. It's also terrifyingly old-fashioned in other ways. It suggests that the GM may want to purchase a screen so that the players can't see you cheat, and the introductory adventure includes instructions to simply not let the player characters do certain things that will derail the climax of the story. It's pretty shocking to meet this again after playing Forge-type independent games for a while, but I am confident that all this crap can be ignored. The system is basically sound and the setting extremely fun. Tweaking task-based into conflict-based resolution won't break anything in there and I can write my own stories (by which I mean "set stuff up for the players to choose where the story goes") easily enough.
We'll be playing Warhammer for the next while, so expect a more detailed post on how it plays later.