How difference between gaman and nintai?

I have read the essay "Sardines in a tin" written by Rebecca Quin in the Jan. 13 edition of The Japan Times ST.  She wrote that "there's this amazing sense of group gaman, I guess, a collective stoicism."  I have no idea whether Japanese people during rush hour in Tokyo have the sense of gaman or not.  But I can't stop thinking about the differences between gaman (我慢) and nintai (忍耐).

These words have almost same meanings.  They are used in the almost same situations. Strictly speaking, both words are not the same.  I can't come up with a good explanation.