I know SC2 is probably a poor example but it fits very well here. It's the difference between managing a team strategy in an RTS versus looking at the individual unit deaths/spawns, types of units, etc.
The two are similar, and you'll often see them combined. For the most part, president pre-dates the CXO nomenclature. Before there were CEOs, COOs, and CFOs, there were Chairmen, Presidents, and Treasurers. Those titles/roles still exist, but are often merged with CXO functions.