When a couple decides to separate or end their marriage, the first important issue that is typically discussed is whether to legally separate or divorce.  The primary difference between these is that when a couple is legally separated they may not marry another party, but if the couple is divorced, they are each free to marry another.  In each, the economic issues and issues regarding the children are decided. 

Another notable difference is emotional.  A divorce is a final break-up of the marriage whereas a legal separation generally leaves people feeling like it may be temporary and give the couple space and time to think things over and, possibly, reconcile.