First, no firearm is sold with a "standard drum". The typical magazine sold with an AR-15 is a 30 round magazine. Except in California and states that have magazine restrictions hat sell the rifle with 10 round magazines. I think you may have some of your terminology mixed up. Drums are available for aftermarket purchase for both rifles.
Secondly, both do the same thing, they expel a projectile out the end of the barrel towards whatever they are aimed at. Their self loading action both do the same thing and they both have a large selection of magazines that can be utilized in operating that rifle. There is no difference in their action and operation. What they are used for is up to the person operating it. So you are saying it should be banned solely on how it looks?