Answer:
For protecting you from crime and/or investigating if/when you are victimized: the police are critical and the soldier is almost useless. In the US, at least, the soldier is also prohibited by law (the Posse Comitatus Act) from being involved (except in very particular circumstances).
For protecting you from acts of war, the answer is flip-flopped. Soldiers, Sailors, Airmen, and Marines become critical, and the police are almost powerless.
That’s why we have both!
the difference between police and soldier is that police is a civil force granted the legal authority for law enforcement and maintain public order while soldier is a member of an army, of any rank.