All the following matches are symbolic links to /usr/bin/vim:

$ find -L / -samefile /usr/bin/vim
/usr/bin/rview
/usr/bin/vim
/usr/bin/vi
/usr/bin/vimdiff
/usr/bin/ex
/usr/bin/rvim
/usr/bin/view

Each starts vim in a different manner/mode, for example ex will launch vim in Ex mode.

The way this is handled is by checking the value of argv[0] passed in int main(int argc, char **argv), clever!