What is the difference between Legal Separation and Divorce?

In Washington, on petition to the Superior Court by either spouse, the court must grant either a “Decree of Legal Separation” or a “Decree of Dissolution (divorce)”.
A Decree of Legal Separation, just like a Decree of Dissolution, must fully and permanently divide the property of the parties, make a child support order and parenting plan if there are dependent children, and make
spousal maintenance orders and require one party to assist the other in payment of attorney fees and grant restraining orders, if appropriate. The only difference in these types of Decrees issued by the court is that a Decree of Legal Separation maintains the legal status of the parties as married, even though their community property has been separated and divorce-like financial and parenting orders have been entered along with the Decree.

Can I obtain a Decree of Legal Separation more quickly than a divorce?

 A Decree of Legal Separation may be issued by the court as soon as the parties agree on all mandatory issues to be addressed in the Decree, without imposition of the “90 day waiting” rule imposed on Petitions for Dissolution.
 RCW 26.09.030 allows the court to issue a Decree of Dissolution only after at least 90
 days have passed since the Petition was filed and served but does not impose the same “waiting period” on Petitions for Legal Separation. However, a Decree of Legal Separation still cannot necessarily be summarily issued by the court: all
 Decrees of Legal Separation must (1) permanently and fully divide all property, if there are dependent children (2) establish an order of child support and (3) adopt a Permanent Parenting Plan and if the circumstances are appropriate, also: (4) award or decline to award attorney fees and (5) spousal maintenance and (6) issue any necessary restraining orders. The court cannot make these decisions
 and express them in the Decree of Legal Separation unless the parties have agreed in writing to the settlement particulars and the court finds the settlement contract to be fair and equitable. If the parties cannot agree on all issues, the Decree cannot be issued until the trial court decides how to resolve the contested issues. Some Washington counties, including King, assign a trial date
 as soon as a Petition for Legal Separation is filed. At present, the King County trial date assignment is just under a year from the date of filing the Petition.
 Thus it can take up to approximately a year for a Decree of Legal Separation to be issued (sooner if the parties agree).

 Can I change a Decree of Legal Separation into a Decree of Dissolution [divorce]?

Yes. Under RCW 26.09.150, either party may on motion to the court seek to made convert the Decree of Legal Separation to a Decree of Dissolution. However, this motion cannot be made until at least six months after the date the Decree of Legal Separation is entered by the court. If one spouse wants to be divorced and the other does not, the court must still convert the Decree of Legal Separation to a Decree of Dissolution. This is because under Washington “no fault” divorce law, marriage must be terminated by the court if either spouse wants to end the marriage. “No fault” divorce is similar to partnership law which also requires the consent of both partners to enter into and to continue the relationship.

RCW 26.09