unix commands not case sensitive?

Howdy,

Perhaps the Unix books that I am using are just too old and not OS X specific. But they all say that the commands are case sensitive while system variables are.

For example ls and LS both work the way as described in the books. I searched the internet and saw concerns using the tab auto completion being case sensitive, but nothing in regard to the commands. But the answers regarding the tab thing lays the blame on the HFS not being case sensitive. So if I understand things correctly, the commands are actually files and therefore fall under the HFS design and there are not case sensitive. Is this a correct conclusion?

Many thanks,

DN