If you are accused of a crime, that means that you are a suspect. Authorities have reason to believe that you may have committed a crime. The police can bring you in for questioning (of course, you have the right to remain silent, and you can have your attorney present for questioning) but they cannot legally detain you. That is, you are free to leave at any time.
If you have been charged with a crime, authorities believe that they have enough evidence to prove you committed a crime. You will be arreseted and detained until you appear in front of a judge for a formal arraignment. There you'll have a chance to plead "guilty" or "not guilty". Usually the judge will also set an amount for your bail and will schedule a date for your trial. You'll be returned to prison, but if are able to pay the bail money, you'll be released and will remain free (usually with certain conditions, such as you are not allowed to leave the state without permission) until your official trial.