my 2.1 cd installed a great deal of stuff under /usr/doc, and the new potato (i.e. 'apt-get upgrade', with /etc/apt/sources.list pointing to 'frozen') puts bunches of stuff in /usr/share/doc.
what's the functional or intellectual distinction: /lib /usr/lib /usr/local/lib /var/lib /usr/doc /usr/share/doc /bin /usr/bin /usr/local/bin /sbin /usr/sbin /usr/local/sbin this topic is covered briefly in one-o-them HOWTOs, which i can't find right off hand... (dhelp search for directories? paths? structure? besides, having just reinstalled everything, dsearch isn't finding squat anyway...) some of these are more obvious to me than others; i bet a couple of you newer debian-user subscribers (like me) are interested in this, too.