Divorce
Divorce is the termination of a marriage. The result of a divorce is that your legal status changes from married to divorcee once the marriage dissolves.
Annulment
Annulment is a declaration that there was no valid marriage from the start. Once a marriage is annulled, your legal status changes from married to spinster/bachelor.
One of the most common reason accepted by the Court for Nullity is that your spouse has wilfully refused to consummate the marriage.