I don't have information to say what's going on, but they're not mutually exclusive.
In 1968, the US had riots in black neighborhoods in different places in the US - burning blocks of cities. They were pretty clearly riots.
But there was a connection to the rage of the civil rights issues behind the riots. It had a clearly political nature as well, even if rioters you talked to would not say that much.
The President formed a presidential commission on the cause which helped identify that.
I'm trying to think of when a protest acted like a riot and was just 'political' without the people being a 'violent mob' caught up in violence for its own sake as well.
One indication: why the people went to the riot, and whether they're 'criminal' type people or not.
When they have employed middle class people, it seems likely there's a political issue.
I'm hearing from UK commentators that the austerity measures are probably contributing; that's seen a lot where they are forced on the public.
It doesn't mean people out in the street with signs, it often means people acting with rage and violence it seems.
The Dylan Rattigan show today has a discussion with US and UK people comparing the austerity issue and whether the US is at risk for similar rioting when there's a trigger.