Who's a Warlock vs a Wizard in HP?

[Rebecca Bowen]

All,

Color me confused - this is a normal condition in my workday life, but for 
my HP hobby not normal at all. :)  Any help would be greatly and most 
sincerly appreciated.

Since DD was Chief *Warlock* of the Wizengamot, I assume that the Old 
English etymology of "deceiver" or "oathbreaker" isn't appropriate here, but 
is the other speculated Anglo Saxon interpretation "the man of the logs" 
(referring to the reading of runes) correct? Or even just "male witch", as I 
have seen some definitions say?  I notice that JKR drops the word "warlock" 
rather strangely to me, outside of use in the Wizengamot and including the 
word in the name of the International Federation or Confederation of 
Warlocks:

Perkins described as an "old warlock" in CoS;
"Wild - looking warlocks" in PoA;
"Rowdy warlocks" again in PoA;
The book "Madcap Magic for Wacky Warlocks" in GoF;
Grubby looking warlock in OoP;
warlocks of Liechtenstein in OoP;
bust of an ugly old warlock in HBP

Is this just slang for a male wizard? Once in GoF, JKR describes one group 
of people "wizards", and in the same sentence another different set are 
called "warlocks." Is it just a JKR inconsistency? It's probably not 
important, but it's not so clear to me and I've always wondered about it...

Rebecca