With the stipulation that there were some punches the USA wasn’t willing to throw. Russia has seen this and Russia has seen Aleppo.

Russia committing to this means that they are okay with doing what they need to for a decisive and quick victory.

This.

The US is certainly no saint in combat. However I will say it is arguably much more sensitive towards at least trying to avoid collateral damage. Russia, and autocracies in general, are probably much more willing to inflict total war because they simply do not have to be as accountable to their publics as a democratic government.