Coke only contains phosphoric acid, not citric acid. However, in some countries, Coke is indeed made with citric acid instead of phosphoric.

Coke changes ingredients around to fit local regulations. In Europe, Diet Coke uses acesulfame potassium ("ace-K"), aspartame and sodium cyclamate. Cyclamate's effect is to neutralize some of the bitterness of ace-K and aspartame, but it's banned in the US and some other countries in the 1950s due to research determining it to be harmful. The ban is being upheld despite later research showing that the original science was flawed.