To be accused is somebody simply saying they're suspecting you. It's a statement based purely on speculation. To charge someone with murder, however, shows that they have evidence and are formally stating that the person murdered somebody else based on the evidence they found. For example: Usually people are charged with murder in the court of law, but a creepy neighbor can be accused of murder any day of the week.

I can accuse anyone I want of murder and it be completely untrue. When the police bring formal "charges" against you, you are charged with murder. You are still accused and could be innocent but you are being accused by someone of authorit

You can use "accused of murder" instead of "charged with murder" and it will still make sense, however if you say the opposite and replace "charged with murder" with "accused of murder" it loses a bit of the meaning. Charges are more of an official accusation usually by the police or some form of authority whereas accusations can be made by anybody.