Difference between mozilla executables

I'm a bit confused as to the number of mozilla executables I've found on 
my FreeBSD system; 'which mozilla' tells me that it's in 
/usr/X11R6/bin/mozilla (it's not a link) but the mozilla help page, 
mozilla -h, tells me to use mozilla-bin, which resides in 
/usr/X11R6/lib/mozilla, along with another binary called 'mozilla'. What 
is the difference between all of these binaries; what is the purpose of 
mozilla-bin and mozilla being there in the latter location?