In the design space you get to be creative with your titles.
Ideally you would want to offer clarity as to what it is you are responsible for.

"creative Director" for the one who is more on the development team.

For the fella working with clients I would try to give him as much power as possible, Keep in mind that a title doesn't designate authority internally, but it does a great job of doing o for prospects. "VP of something." works well in my experience.

If you need additional inside please feel free to reach out to me!