Challenge Points are cumulative; a reward system that affects the level of your ranking in leaderboards.
For example:
Any challenge points obtained are directly added to your overall points, and this affects your ranking position in various leaderboards e.g., Hero of the Day, Top Brain, etc.
KoKo Credits are consumable; a reward system that helps to improve your learning experience.
For example:
KoKo Credits earned can be spent on unlocking premium features, such as StoryMath chapters, which will help learning maths through comics.