The difference between this skill and intimidate is intimidate involves scaring and threatening people into doing something, and tortue involves hurting people, which makes them more easily scared.
Under my system, missed checks deal more damage, which is bad because you want the subject alive as long as possible. Also, higher level characters, even ones with poor will saves are a lot harder to torture than low level. An experienced mid-level character, (such as a typical navy seal) must be tortured for several hours before they begin to crack.
And of course, these rules are for NPC, especially the clerics of elemental evil, and not for PCs.