Differences in Brands for Traffic Drums?

When it comes to different brands of traffic drums (work area protection, TAPCO, Bent, etc) are the specs really that different?  This is something I have wondered for awhile, because to me it would seem as if there is no reason to change the mold of the drum if it meets the specs that need to be bet.  But, there are differences.

I know that in some brands the base and bottom of the traffic drum is shaped in such a way that if it tips over it will not role around, but get caught and stop rolling.  In other brands they are circular but have a ‘lip’ so that it gets caught before it keeps rolling.  Another difference can be the height, which I have seen at 39″ in some models and 42″ in others.