On the other we have hooligans organized for the express purpose of overturning the results of a democratic election.
In the case of BLM, the crimes don't reflect on the movement's overall purpose. Nobody expects property damage to be a vehicle for police reform -- it's an argument for more police presence, if anything. In the case of the capitol riots, not only are the crimes worse (storming the capitol >> property damage), but the criminal acts absolutely do reflect on the movement's agenda. Intimidating congress is a plausible vehicle for obtaining the votes they needed that day to overturn the election. Trump's pre-riot speech emphasized that this was the goal. These factors increase the culpability of platforms and leadership in the capitol riots as compared to BLM.