well actually as for the difference in appearence, warlocks may b called as male witches who mostly use their powers for evil so they're plus ou less human in appearence but this doesnt necessarily differentiate them cuz even lower level demons may look lyk humans (plus we have cole...). The main difference i think, is that warlocks can steal the powers of a witch and use it against them and this is mostly why the Charmed ones sometimes hesitated 2 use their powers against warlocks ....
