So also are /usr/bin/{cd,[,echo,pwd,fg,..etc} a lot of them having subtle differences with their corresponding shell builtins. Most of the time the differences

So also are /usr/bin/{cd,[,echo,pwd,fg,..etc} a lot of them having subtle differences with their corresponding shell builtins. Most of the time the differences are not worth the hassle to remember, unless you somehow end up on a system with a broken filesystem (for example where /lib or /usr/lib is destroyed) and need to rescue stuff.