Arrested -- This means that you were taken in to custody by the police. Once you are taken in to custody, it will be decided if you will be charged with a crime. Someone who is arrested is not necessary charged with a crime.
Charged -- Once you are in the custody of the police, the prosecutor's office (aka state attorney, district attorney) will decide whether to charge you. If you are charged, you will be given a charging document (sometimes also called complaint or information). This charging document will state exactly what crimes (charges) you are facing.
Sentenced -- Being sentenced means that the "punishment" you got when you admitted (pled) you are "guilty" or when the judge/jury decided you were "guilty". If you were placed in jail/prison, probation, community service, or mandatory classes, you were sentenced.
Alternative Sentencing -- Sometimes called "differed sentencing". A court may require you to satisfy certain conditions (such as community service, classes, etc) in exchange for a dismissal.