alright, this has pissed me off for quite some time, so I think I better weigh in here. "Smells Like Teen Spirit" IS NOT the same chord progression as "More Than A Feeling". Here's how it breaks down (some minor music geekery lay ahead):
Teen Spirit, from what I have always known, if played in the key of F-Minor, with the famous riff using a I-IV-III-VI progression. Now, that key may have been transposed (I dunno, maybe they downtuned) but it is still that progression.
More Than A Feeling's famous riff can be played in the key of G Major, utilizing the chord progression I-IV-VI-V.
Even if they are played in the same key, they are different chords. I admit, there is a similar feeling to both parts, but I think that might have to do with the dynamics of the song (each is somewhat of a release of tension and quite anthemic).