IS = an ideological network of individuals hiding among civilian populations across the globe
US = an nation state with an identifiable military subjected to rule of law
>and both sides are very clearly not very precise in who they actually target (the bombing on Doctor's Without Border, anyone?). Both sides cause tons of civilian casualties
For better or worse the US is operating on intelligence specifically designed to avoid/minimize civilian populations, which is very difficult when IS doesn't wear military uniform (as required by the laws of war to distinguish military actors from civilian populace) and hides among civilians. I don't know if it is "tons" or what that even means in relation to human death figures, but I'll concede it happens, still it should be defined as collateral damage because the goal of US operations is not to kill the civilian populace but those individuals bearing the most responsibility.
On the other hand IS specifically designs its quasi-military attacks to be inflicted directly on the civilian populations with the goal of maximizing civilian casualties.
These are not just differences in justifications, but differences in actions...at least according to the law. Now I could see your issue if the US was secretly funding, training and arming non-identifiable combatants and recruiting/embedding them all over the globe to specifically orchestrate indiscriminate attacks on civilian populations.