The type command, like which, locates an executable file in your shell’s search path:

$ type grep who
grep is /bin/grep
who is /usr/bin/who

However, type is built into the bash shell, whereas which is a program on disk:

$ type which type rm if
which is /usr/bin/which
type is a shell builtin
rm is aliased to `/bin/rm -i'
if is a shell keyword

As a built-in command, type is faster than which; however, it’s available only if you’re running bash.