Cream or butter in a pudding I wish to know what would be the difference between using cream or butter in a pudding.

I have never used cream instead of butter and do not even know if maybe both can be used at the same time?
Butter helps to set whatever you're incorporating it into more firmly. It's also delicious.

Cream is liquid and will remain liquid, unless whipped and incorporated. 

Honestly, it all depends on what you're making. Sometimes they can be interchangeable and sometimes they definitely cannot.