Filesystem

/boot/efi has been deprecated
/etc/mtab has been deprecated
No /lib32 and /lib64; pure 64-bit system
No /libexec
No /run/tmp; only useful for embedded systems on Debian
Sticky bit (1777) is set on /tmp and /var/tmp (and /var/mail?)
/usr merge
/var/db has been deprecated; a BSD relic that has been replaced with /var/lib
/var/lock is symlink to ../run/lock for compatibility (/run/lock)
/var/run is symlink to ../run for compatibility (/run)
/var/spool/mail is symlink to ../mail for compatibility (/var/mail)

Resources