fairly major difference is the intent.
civilians getting killed as a consequence of war is one thing - presuming those civilians werent deliberately targeted then it isnt necessarily an evil act simply accidental.
Deliberately picking off civilians in an area where a war isnt even being fought is completely inexcusable. Even the Israelis have a better moral standpoint with regard to civilian deaths in Gaza & the west bank than the Chinese have regarding Tibet.
There is recorded testimony of American soldiers knowingly shooting civilians since at least WW2. You shoot someone, dig a hole and fill it in. Same with the UK. Possibly every country in the world has had soldiers do this. In no case is this an accident.
The Chinese government would claim they are up against dissidents, although you and I would disagree with that. America claims its up against communist sympathisers and guerillas, with again no proof offered.
There is then the use of American agents in central and South American countries as well as Asia. Same sort of thing happening, people being murdered because of their beliefs.