Count vs. Darth?

This is my first post & I apologize if this has been covered elsewhere or for being so dumb as to not know the answer. I've also used the search function but was unsuccesful.

Anyhow, why was Dooku "Count" when every other Sith Lord/Apprentice a "Darth"?

Thanks!

 

Well, Count was a title he inherited! It had nothing to do with being a Sith!

 

count dooku = darth tyrannus

 

Tyrannus was his Sith name. He just happened not to use it much I guess.

 

Count Dooku = public name
Darth Tyranus = private name

 

Thanks all!