I think maltodextrin is in some foods. It is a filler in all of your NO supplements...the powders, anyway. It's a complex carb. Dextrose is corn sugar...it's a simple carb and is therefore more quickly digested. The purpose of taking them is to prolong/intensify your workout. They are used to replenish/fuel your glycogen stores which are your chief source of energy.

Someone let me know if all of that is correct.