Clemenceu is the same of that Richie except it has more ammo, DP but it got 1 more support slot and same speed and they use the same guns...

while Jean Bart  is like beef up Richie with Alsace's cloned guns, it only goes 40knts, 7 support slot only compare to Clemenceu with 8 supports slot, got near tight spread than alsace, but its fun to play rather than making it a leveling ship

Simply put:

The Clemenceau is a leveling ship. Its purpose is to help the grind by increasing the number of sailors you can level at a time. Other than that, it's not much different from the Rich. I would recommend this if you don't have a full BB5 level crew yet.

The Jean Bart is a fun ship. It's meant more as a "cool" thing to have, and works best if you have a BB5+ crew already.

I hv both ship.
I think if you like more speed, clemenceu.
I you like power and fun  jean bart.

i  don't like fun, so i pick clemenceau?

I used the Jean Bart for some fast leveling. The spread was the same as on my Clem, but only more damage. Speed wise it didn't matter, because the crew was at level anyway. 

It took me way less time on the JB than on my Clem, but well another reason for that was that I am not used with using 35 degree guns. The JB has a 40 degree gun, which I found way easier to use.

I am one of the few who found leveling on the JB easier than on the clem, as I noticed in GBs:P